It's looking nice so far, though I don't think I'd be able to give any really detailed insight without first taking more time to get more familiar with the fortress.
Anyway, here are a few things I noticed that may be useful to consider:
If you happen to get sieged in future, be aware that trolls may destroy any buildings they can reach, such as the ones outside if they are left unprotected.Some of the workshops are "cluttered" (CLT) with created items, and this will slow down production at those cluttered workshops, slowing down further as the clutter increases. It won't stop production completely, however, so it's up to you whether you want to increase production speed by creating sufficient stockpiles for all of the clutter to be hauled out of these workshops.
I think the barracks work just fine if you define them from just one bed, as long as the room you define covers all of the beds that you want to be part of the barracks. The game considers rooms with overlapping floor space to be "shared", and although this doesn't stop the dwarves using them, it will make them view the rooms as less valuable, and therefore less pleasing. I'm not sure whether this rule affects shared barracks, though.
Dwarves like to organize parties, and parties don't involve doing any work. They can boost happiness and develop social skills though, I think. Dwarves will organize parties in unused rooms defined from certain furniture, such as cages, chains/ropes, wells and statues, as well as dining rooms that serve as meeting halls. I'm not sure exactly what triggers parties, but you can stop them at any time by [f]reeing any unrequired rooms where parties are taking place.
Although a refuse stockpile outside will get most rotting items out of your fortress, a grave[y]ard stockpile is required for any remains of dwarves or pets that aren't assigned to coffins. I found the refuse stockpiles, but I couldn't seem to find any graveyard stockpiles when I looked, so adding one outside may help to prevent miasma.
If you get any criminals while you have a Captain of the Guard assigned, said criminals may be given a beating as punishment, and most certainly will be if you don't have enough cages or chains assigned for justice (press [z] and view the Justice screen to see how many "Cages&Chains" you need, at the top right). However, if you don't have a Captain of the Guard assigned, criminals are pretty much safe, until a Hammerer arrives.
Although traps are often considered overpowered, you may wish to invest in some at your entrance, just in case goblins decide to attack. By "traps", I mean stone-fall traps, weapon traps and cage traps, though you can devise more complicated traps too, if you like. The basic requirement for all traps is mechanisms, but you'll need stones, weapons or cages too, depending on which types of trap you use.
Don't worry, none of these things require urgent attention, but they should be easy enough to deal with anyway. The fortress is looking good, and I like the name, "Manytombs". Hopefully it's not a sign of things to come.
I hope at least some of this may be helpful. Good luck!