^Don't worry about it. 'WASD' will very quickly become second nature. The only tricky part is the space button, which for some reason Bioware decided to assign about 50 different situational functions to. It can make running away, diving and getting in and out of cover a bit of a toss up as to which you intend to do and what you'll actually do.
Honestly though, just stick to the bronze matches and you'll be fine. Basic rule of thumb: any character still below Lv10 should stick to bronze; Lv15 and up should be OK for gold. Needless to say the new platinum difficulty is for experienced Lv20s only. It's also worth noting that unlike SP, in MP soldiers can be one of the hardest classes to play. For the high level matches, it tends to come down to either asari adepts (for the warp/throw detonations and of course the stasis bubble) or infiltrators (mostly geth or salarian) with widows for sheer DPS.
Realistically, once you've got your characters levelled up you'll be spending most of your time in silver matches. Unfortunately, most gold matches are most often used for credit farming. If you come into a lobby and see it says 'Gold, Geth & Firebase White' at the top of the screen then you'd best leave unless you want to spend 10 rounds camping over on the far left with everyone else. It can get very dull.