I have three boxed on a laptop at times with no issue for years when I am away from my desktop machine. And I know of at least two people I have met in the past few years that play through a hotspot tether. As said above as long as you have enough data, you will be fine. I did know another guy who used a hotspot that would occasionally have issues going linkdead in certain situations, but I think that was more of an issue with his carrier than anything. Even with him it was not often, just at times, and I do not know if there was a common catalyst involved causing it or if it just sometimes flared up. It got annoying during raids when it happened lol. But yes, you can play on a lot of laptops just fine and hotspots are used by people without trouble. Not sure about the Surface question, as mentioned it would depend on graphics hardware and ram.
I think it still holds true that each instance of EQ takes roughly two gigs of ram nowadays (seen that tossed around). It seems to be the truth because I had a computer I boxed on break down and used a back up that I threw together that ran Windows XP and four gigs of ram and all of a sudden I could two box just fine but would have indescribably insane lag and lock up after a couple of minutes trying to boot in a third account. On my new Windows 7 box with 16 gigs of ram I have run up to six separate instances of EQ with no lag at all. EQ (used to be at least, since it is older) a more RAM intensive than graphics card intensive program, though modern optimizations may have rebalanced that some. It is hard to say because I also have a higher end graphics card, but I know the memory made a massive difference. All of this is not exact, but I know it is at least partly accurate. YMMV but as long as you have a halfway decent graphics card and enough ram. EQ is very easy to run on many different levels of configuration depending on the number of accounts you have running at the same time.
Edited, Apr 16th 2015 7:09pm by Rotxam