Media Center-few noob questions,subtitles,sources,etc.

Hi there,
Maybe those question will look funny to most of you,but even I'm using win7 until beta700,I've never used Media Center until I made last repair install.
I was just curious,why is that desktop gadget so important,and that's how all started.
I looked over last few pages of this section to find what interests me,but still I heva few questions to ask.
First of all,is it possible at all to start Media Center from somewhere else then gadget,or gadget is it's default place?
My second question is related to videos and movies-subtitles.I checked the option"show subtitle",not just "when mute",but always and I can't find anywhere else where could I enable subtitles because I don't see them when playing .avi movies from pc library(still haven't try to play them from DVD player).Most of my titles are with .srt extension,and of course,named same as movies,and working in other players.Do I have to convert them to some other then .srt,or there is some other way to load subtitles?
My third problem is related to analog TV tuner card.I have an old analog Gigaybte Tiger 2 card,with Philips SA7133 chip inside,but have 2 sources input through the switch,cable and air antenna.
When I'm setting TV input in Media Center,I have both options to choose FROM,but when I'm done with with first one(no matter which I choose first),and when start the other one,all channels I saved in first scan are gone.Is there any way I can scan for both sources,and saved all channels?
And just one more(for now).
I can't find the way to start movies with remote control.I have options for video,for TV,for FM,snapshot,channels,back,arrows...but in none combination,no matter pressed together,or one after another,of those buttons I can't start movies.Maybe I would succeed with arrows if remote would start in main menu,but it doesn't.
Thanks in advance