Cable TV ISP Broadband Security Issue

Recently I have switched to a local Cable TV Internet Service. These guys do not provide any modem inside the house. Their modem is located outside from where various branched-out wired lan connections are provided to customers.Thus I have a direct lan cable into my computer's lan port. Now the problem is when I go to My Computer -> Networks, I can see a bunch of unknown computers ( who are of course the other consumers and may be an admin). 

https://drive.google.com/file/d/0B7N9qFV5QrtneGZfQnBtejcza2c/view?usp=sharing

I was worried if any of those computers could actually access my files. So I tried to access theirs from my side. I was surprised to see that any computer without a windows password could easily be accessed. For example \\jack-Pc\C:, was showing shared drives on that PC . Those with windows password could not be accessed though.
Just to make things clear, this has nothing to do with internet connection. Whether the internet is on or off, just the lan cable plugged in shows all these computers. 
If I turn off network discovery all the computers vanish, google tells me that network admins can access files inspite of network discover/file sharing settings. If I run 'net share' in command prompt it shows all my drives have admin share. So I am afraid that the admin of this stupid network (who could be the isp guys) can actually access my files.Well I googled how to turn admin share off tryu regedit and applied that, but I have the following questions in mind.

1) Can a network admin access my files and folders without knowing my windows login credentials?
2) If i disable admin share thru regedit, can he still access my files?
3) I have noticed putting a router in between the lan cable and my computer, makes these computers vanish. So can my personal router serve as a security shield in this case?

Just to add, unlike in corporate scenarios where network admin has all rights and the user doesn't have admin rights, here I have complete admin rights on my machine. I am just afraid if the n/w admin of this network also shares the same privilege.

another point: My antivirus is warning me of duplicate ips, when I am connected to this network.
https://drive.google.com/file/d/0B7N9qFV5QrtnN2hrWkJ0eFJYQWc/view?usp=sharing

 

ps: These guys are no tech guru, so I am not afraid of someone brute forcing my password. Just want to prevent easy regular access t my private files due to my ignorance.

Wow, that is a strange setup. You do need to ensure sharing is turned off on your system. And no, Admin cannot see your files and folders if your sharing is turned off.

If me, I would buy and insert a router between your computer and that network connection.

Yes I have already connected a router, and had it's default id/pass/ip changed. 

I was just worried, while the router was not in place, whether the isp network admin could have had bypassed my windows password and accessed files in spite of sharing turned off. Many people over the net are telling me that inspite of file sharing off, all drives have by default admin access, which can be verified, via the 'net share' command in command prompt. And indeed the command shows every drive has admin share. 

But i kind of understand, that is only possible when I belong to the admin's domain, which is not the case here probably. 

Any thoughts?

That is not the same admin as the computer/OS admin.

The ISP can certainly see everything that goes through their network, but the vast majority of that will be encrypted.

Where are you located? What ISP? By far, most ISPs are honest and have no interest in violating your privacy. In fact, they tend to be more concerned in blocking government spying on your data than doing the spying themselves.

I am located in India. Currently here there are a lot of Cable TV guys, who are providing internet over Network cables. The speed is better than what established companies provide, and at a much lower price. The problem I have encountered, is in fact experienced under all cable TV Broadband providers across the country. No such problem arises if someone is using 3g/4g dongle or wired adsl connection. It is specific to TV broadband cable. I guess it is more of a faulty protocol that these small companies follow, rather than an individual trying to snoop in. I am not worried of my data going thru the network. That can be encrypted by VPN or whatever. I am just concerned about my own personal data on hard drives, which I hope was not open to the isp guys while the router was not in place.

If you have kept Windows fully updated, used Windows Firewall or suitable alternative, used a decent anti-malware solution and kept it updated, AND you avoided risky behavior like illegal file-sharing via Torrents or P2P sites, you do not visit illegal pornography and gambling sites (places where badguys wallow), and you are not "click-happy" on unsolicited downloads, attachments, and links, your personal data should be safe. Now there is never a guarantee your computer cannot be hacked. If a professional hacker has personally singled you out and targeting you specifically, they can get in - just as a determined crook can "eventually" break down the front door of your home if he really wants to get in that badly.

 

But badguys are opportunists - they go for the "easy pickings" and won't waste their time if they see any resistance. They look to see if you left your keys in the car, or your front door unlocked or an alley window opened, and if they don't see an easy way in, they move on down the street.

 

Same with your computer - keep Windows and your security programs updated, stay away from bad sites, don't invite the badguy in by being "click- happy" and use strong and unique passwords. Then, when a badguy comes around snooping and sees you have established a formidable defense, he'll move on to easier pickings.

 

And remember, "socially engineered" methods of malware distribution is the most prolific and successful method. This is when badguys create official and authentic looking sites and links with "inviting" offers to entice unsuspecting and gullible users to click on and visit. So don't be click-happy!