A Few Questions about the HTC One / Android...

So, basically, I've been using iOS (mostly jailbroken) since 2009. I have no experience of Android whatsoever.

I've said in the past, even on here a few times, that I'd like to give Android a try but didn't particularly like any of the handsets that ran it. This has changed with the One, black model.

It seems the major criticisms it receives are the lack of removable battery and expandable storage, although coming from a 16GB iPhone which has about 5-6GB free I'm of course used to these 'problems' so it's a bit of a non-issue. There's also the camera but i guess time will tell on that one. I tend not to be much of a photo taker anyway - I shoot more videos than photos. So, I'll give it a good fair try and if I don't like it or find it difficult to adjust I'll probably end up getting the iPhone 5S or whatever when it's released.

I have a few (possible noob) questions for you guys though:

1. Can it be rooted out of the box, will ROMs such as CyanogenMod work on it?

2. Can the Sense skin be removed from the phone and have it running stock? Via rooting or otherwise? I've seen this guide:

http://www.theverge.com/2013/3/23/4132926/nexus-look-on-any-android-phone

But I'd rather do it properly. Is there a 'stock Android' ROM?

3. If Q2. is a 'NO', I've read that Sense doesn't have system toggles in the pull-down NC - can I add them?

4. Is the One likely to be updated to Key Lime Pie or even 4.2 at any point?

5. I use a MBP, do Android phones play with iPhoto? As said above, I've been using iOS since 2009 so all of my photos and videos are kept in iPhoto so I'd like to keep that going, if at all possible...

Thanks for any help, apologies if any of the questions are stupid...