Windows 10: Windows 10 vs Windows 8.1 on mobile

I know that I post this on wrong forum, but I think that this is the best forum ever, so..
-I'm going to buy a phone.I don't like Android phones 'cuz EVERY phone I buy it says APP ISN'T RESPONDING on EVERY app I've tried!!!..Only phone that don't stuck that I saw is Galaxy Grand Prime. But it has another problem-PRICE.

I have in plan to buy Windows Phone. I found (for me) great models Microsoft Lumia 535 and 640. Does anyone has this phone? On what OS it better runs?

:)

 

can i develop for windows 8.1 on windows 10 after windows 10 upgradation

I have windows 8.1 installed on my system and i am eligible for the free windows 10 upgrade.

I am using this machine for the windows 8 and windows 8 mobile development.

So I have installed lot of software installed on it like visual studio 2012 , 2013 , SQL server 2012 expression blend

and so many............

After free upgrade to windows 10 can i continue developing for windows 8 with vs 2012 or vs 2013??

or i do need vs 2015??

 

Roll it back to windows pro 8.1

Original Title: windows 10 pro vs windows pro 8.1

I purchased a Surface Pro 4 with windows 10 pro, as wiindows 10 sucks can i roll it back to windows pro 8.1

 

I have a Lumia 640 XL and I upgraded it to Windows 10. The phone runs great. It came with Windows 8 but I was never a big fan Windows 8 so I upgraded to Windows 10 the first day I bought it. I much prefer the Windows phone over my old Galaxy III.

 

I saw that in Serbia market it is very expensive for me.. I have a battle in my mind: Nokia 432 DS vs Nokia 535 DS vs Nokia 532 DS.. I've googled for 532 and it is best for me, 'cuz of it's price. Do you know someone who has one of theese phones? What experience was like? How GPS is working (is it good or not)?? I heared that HERE Maps work without internet, is that true? I also found on the net that 535 has touch problems in 8.1, is that huge problem?