My best experience migrating a legacy system into a VM was with Acronis True Image with Universal Restore. I took the drive out of an old P4 Dell running XP, imaged with True Image, created a VM, booted from the recovery iso, and used universal restore feature. Worked pretty darn well, much...
Might want to look into the Intel NUCs, some run of 12V power according to this review: http://www.legitreviews.com/intel-nuc-dn2820fykh-bay-trail-system-review_135053
Only 1 sata port, but there is USB3 on board.
1. Windows has a bit of a habit of delaying boot up processes a bit to reduce I/O overload (in my experience). I would just test with the stop watch and if it's under 30 seconds to desktop after BIOS, things are good.
2. Newer built in drivers?
When I got startisback, which came about 3 months after launch or so. The lower ram usage, faster boot, and faster installs made me switch. Also not having to deal with 4 years of extra updates and crap.
I've noticed this too. Windows and applications will make use of the extra available ram as buffers and caches, rather than too read from storage and process through the CPU, it can near instantaneously get it from RAM. Unused RAM is wasted RAM, as RAM can be flushed extremely quickly.
Minimum is SSL/TLS security, and some good security hardening from the hosting company.
I would use Google Docs for forms if you're on a shoestring budget, or give Wooforms a try (heard they're good, but haven't used it for myself - http://www.wufoo.com/)