to answer your questions:
titanium back up does save your data. the program also allows a user to restore this data. the trouble is, especially when moving from rom to rom to rom programs do not always work quite right when just restoring them. as i state below i always download the apps again and just restore data to them via TB. for old programs no longer available on the app store i have restored them via TB.
if i remember correct rom manager can back up your existing rom. this gives you a "restore point" if you want to think of it in windows terms. this program also allows you to install roms. think of it more as "dos" on a windows machine. rom manager has a front end which works inside android and a back end which works as a recovery service. think of it like the menus you get on bootable dvd roms (like the windows disk) except it is on your phone and not on a disk.
yes, rom manager (well actually the recovery portion of the program) can install the rom for you. i think there is an option in the front end of the program to do this but i HIGHLY suggest going into safe/recovery mode and doing it via the back end. i've had zero issues going that route. dont forget to wipe (see steps below)
all roms that i have seen come in a zip file. you leave them in this format when using rom manager.
no trouble for the help. we were all there at one point or another. i remember how hard it was for me to find information.
---
in general when moving from one rom to another this is the list of steps.
-install rom manager if not installed
-install titaniumbackup if not installed
-back up your current rom with rom manager (if i remember correctly) and put this on your actual phone. trust me, do not ignore this step as it could save you problems in the future if you ever get into a nasty situation.
-back up all apps, app data, phone numbers, etcetera
-go into your phone number listing and manually back it up via the menu button and subsequent screens.
-pull back up data and all photos, ringtones, etcetera which you dont want to lose to your sd card. and preferably your pc but the install does not affect the sd card so you should be safe with a sd card backup. i just like to play things safe.
-download the rom you want to use
-turn off the phone
-restart the phone in safe mode/recovery mode, rom manager recovery should start
-verify that you can navigate to the install zip file (but dont install yet)
-wipe davlik cache and data
-install the new rom via the menu system
-wait about 5 minutes
-the phone should start up
-flip through some menus, in general navigate around the phone and check functions to see if there are glaring issues like lagging, menu sticking, etcetera. if not then continue. remember to give the phone a few minutes to boot up as it may have some cpu processing to do at first.
-NOTE: some roms do not come with google apps! remember if yours does not you will need to manually install the .apk once you download it. personally i prefer using roms which include google apps. at minimum you will need googles app store or a copy of titanium backup and rom manager you can install via .apk
-navigate to the google store and get a copy of rom manager and titanium backup installed asap. this is your first priority above all else.
-update your cell tower listing with the code your phone company gave you
-with rom manager (or via the phonebook menus) pull back your phone numbers
-i highly suggest downloading your apps again instead of installing them via the backup files. what i do is download the apps and then restore data only. i havent experienced any real issues going this route but i have had a few minor issues going the other way. mostly with them not wanting to install in some rare cases.
-pull back photos and ringtones to your phone
-set your phone up how you want. ringtones, backgrounds etcetera.
if you dont like how your phone looks... give golauncherex a try. yes, it works on sense phones. what it does is replace the stock launcher (that hideous bar on the bottom of the screen with phone, app drawer, and other buttons), the app drawer, and control over how many screens you have. i have mine set to 5 icons across with swipe up actions. that is 10 different actions i can set with less than 1/4" of height.
i use this: format... command/swipe up command
phone/phonebook
camera/photo album
app drawer/email
text message/google mail
web/app store
it definitely saves alot of time over the sense interface! but then again, i like minimalist designs so i dont have many icons on my desktop. just a recommendation of something to try out.