Congrats on your TA-30 purchase! You're gonna love it! It's been my main amp since I got it in November 2015, leaving my other 9 amps gathering dust (including a Duel Rec, a Vox AC15C1, and an original 1977 Marshall JMP-1 MKII and a 1981 Marshall 2203 JCM800). The TA-30 not only sounds great, I find it way more useful and versatile (and more manageable volume-wise) than my other amps.
Regarding Tweed mode, it's been a while since I've used it, but it seems to have the least amount of overdrive of any of the modes on either channel. I'm not a Fender amp guy, so can't tell you hat it's based on, but when wound up, it doesn't get very crunchy. It gets clippy, a bit hairy and compressed, but almost in a power amp style distortion than preamp style. I might be told I'm completely wrong, but I learned quickly I don't like driving the Tweed mode into overdrive. If I'm going to use Tweed, I set it to a nice clean tone, and then wind up the Green channel in Top Boost mode to give me my overdrive sound.
I thought I heard somewhere that Hi 1 mode is supposed to be based on a JTM-45. Maybe that's true on lower gain settings, but there's way more gain on tap than I think a JTM-45 would have, even before you engage the gain boost (I've never played a JTM-45 though). With the gain boost engaged and wound up, I think you could get into moderate JCM800 gain territory.
Regarding how much the reverb & loop adversely impact the Green channels sound, it doesn't. Not in any appreciable manner and certainly not live in a band. The reverb sounds great, and so does the tube buffered FX loop. Use them. The reverb can be a tad noisy at higher levels (I love the reverb, but I only want a very light amount - on my cleans, even at just less than 9:00, that's about as "wet" as I want to go). But the loop and reverb and loop have a hard bypass mini switch if you want to quiet the amp down for recording. That's the only time I'd disengage the reverb and loop.
Be aware however, the earlier TA-30's had an issue with noise reverb. Mesa developed a fix for this (I had the mod performed as mine is an earlier serial number, despite buying it in 2015) and now its really quiet (for a real spring reverb). If you find yours especially loud, contact Mesa and they can assist you in determining if yours would benefit from the reverb mod.
Hi 1 is usually what I usual use for my overdrive sound live with my band, in 40W with the Bass and Treble almost at 12 o'clock (adjusted slightly depending on the guitar, the room and what cabs I'm using that day). I engage the gain boost, and keep the gain between 2:00 and 3:00. Stomp on a Tubescreamer type pedal with level high and gain right down for solos to cut the bass and mush the mids, and it's incredible.
My fav clean sound for my band is Top Boost, with the Tone Cut pull out to become a Master Volume so I can dial in more gain to get my clean tone just starting to breakup a tiny bit is I really dig in hard. For my guitars, that's with the (preamp) volume between 11:00 and noon, in 30W mode, and Bass and Treble close to noon again.
Despite not changing my settings much in my current band, it's a serious versatile amp.