Can't answer all the people, so I will answer what I remember.
I really need to work on my recoil control, im tagging so many players and missing kills, 23+ assists in just 2 games yesterday with 40 in something like 5. Im playing pretty regular with these lads and some of the game are a real challenge for me as generally most of the opponents are 4+ ranks above me but it is hellafun and like you I never used my mic, never even played any sort of strategic game in any fps but it is my favourite part of playing with a group of friends now and what makes me love GO.
I am improving and enjoying it even more for it. The banter is hilarious sometimes too, Zeus rounds for the win! we didn't, not with the Zeus atleast.
You are improving a lot. yesterday you had a +5 kill spread against GN4/MG. Sure you will get ranked up soon

I also don't play a lot with team mates/using microphones, so it's quite good fun. Plus it's the community which makes you like a game.
Was gutted the other night when you invited me and I had to rejoin Steam and when I did the match had started. I'd been waiting for someone to come on all night.
As a say just want to find some regulars.
There are no fixed regulars. Me, JS, Sound, Prox, r0ss, Flighty, Spaghetti, Bakht, Pauly, Sabre (and some others I forgot) generally party up a lot. If you have those guys, you will 100% get an invite. Sometimes we split in two because we have more than 5 people.
is it preferable to have a hiher DPI and lower in game sens or vice versa. Currently im using 400dpi and 4.00 in game
Multiply DPI with sensitivity. Most pros use from 400-1000, but I am at 1500. Practice makes perfect. No mouse/keyboard/any gear will make you A LOT better (well, unless you are using a trackpad).
Was gonna bet on NiP for NiP vs Na'vi, thankfully I did not. Na'vi lost to mouz, then beat NiP. **** YOU NA'VI.
I use a 60hz screen. it should make a difference but as I said, I won't buy new gear to get marginally better at a game.