There are several apps for accessing Google Drive from a windows phone. A couple of them are G Drive, Gdrive.net, and Metro Drive. Of course, you don't need an app. You can simply go there from the browser in your phone.
I'm not sure I would agree that android is more secure or more stable. I don't know the current statistics, but in 2015 Alcatel-Lucent reported that over 60% of all mobile device malware is found on android devices. They are the "big player" so it makes sense that they are the target for malware writers. Windows phones were only about 4% of the consumer market (and that is probably declining) making them much less attractive targets, but they are still windows OS so there is some malware that will attack them... but it's very rare. The bottom line is that both are actually pretty secure and in either case the risk is much more dependent on the user than the OS. I will say that I know a few businesses that only allow their management to utilize Windows phones because they believe they are more secure... but I can't say I understand their analysis to arrive at that. The only part that actually makes sense to me is that I have a client that is a national seed and chemical company. They only let their people have Windows phones because they believe they have more control because they know what apps they have on them and how they will interface with the rest of their computer systems - thus they feel more secure.
As far as stability, I'd say both systems are pretty stable. Android updates there system on a regular basis. Windows almost never updates theirs. I'm not sure that is really a true indication of stability.
I've told you before, I use a Windows phone because of it's simplicity. I currently have a Lumia 735, the only Windows phone on the Verizon system. Verizon hasn't approved Windows 10 on phones so it comes with Windows 8.1... but I installed Windows 10 on it through the Microsoft Insider program and I really like it.
The radios in the phones that allow them to communicate with both wifi and cellular network are very similar. I don't believe that there is any appreciable difference in most phones. However, app availability is exponentially larger with the android system than on the windows phone. People are just not writing apps for the windows mobiles. In many cases it isn't a big deal as we are talking the difference between having the choice of 20 chess apps on a windows phone and 200 on an android. You can still play chess. I find it very handy to have Microsoft Office come with my windows phone. I can easily modify excel spreadsheets on my phone. I also, using the Remote Desktop app, can "run" my computer at my office from my windows phone from anywhere I have a signal. These things can be done on android also... but I just find it extremely easy on the Windows phone. I've stated elsewhere that the decision on what phone to use was pretty much strictly due to my father. We got a loaner Iphone, a couple different androids and a windows phone and had him use each one for a week. He didn't make it the whole week with the Iphone before he got frustrated. He was able, with some difficulty to use the androids, but it was a challenge. He had no problems using the Windows phone. He found it to be fairly intuitive from day one. He actually "test drove" one of the androids, then the Windows phone, then the other android. He wanted the Windows phone back before completing the week with the second android. That was like 5 years ago and I doubt he would even be willing to try one of the other systems today.
All of that being said, Microsoft doesn't seem to be doing anything with the phones. It appears that they are willing to just let a good thing die on the vine. I truly wonder how long they will continue to be available. I will say the pricing on them is good. I have a business account so my pricing is different than what you can probably get, but I upgraded one of my superintendents phones to the Lumia 735 just yesterday. The new phone cost $29.95. I don't think I could get any new android phone for that price.