<1. Hometown> As mentioned by Koch, having a multidimensional town or a region with supporting towns would serve the characters. A large city with an outer busy crossroads and a few remote villages, then a peppering of way houses, a few hidden elf homes, a couple dwarven forts or mines, some religious bastions, and a crumbling borderland keep? Hey, throw in a ramshackle dilapidated port on the edge of the sea and a marsh town along the brackish tidewater! It’s not too hard to pack the town types into a metropolitan mishmash. And, having a bit of space between, like little exurbs that fringe each town, means the characters might have to actually travel between the towns depending on their needs or wants.
<2. Town Events> As mentioned, keep those. And, this might be encouraging for those portions of the larger settled region as the characters move around in different places. If they’ve caused a bit of disaster in one spot, they can head to another location nearby or try to resolve the disaster. But, it doesn’t have to all be happening to a single town that’s sooooo small that disasters are felt in every corner.
<3. Missing Sessions> I would place a higher requirement on commitment for players and a smaller number of available seats per session. I simply wouldn’t let it be such a “Dungeon/Monster-of-the-week” style of campaign. Force, no. FORCE your players to pick factions, write hard-hitting beliefs and creeds, write challenging goals, and engage with the setting and other characters. Absolutely hold their feet to the fire and do not let up! Make it an absolute ironclad requirement. Otherwise, send them packing. They can find another game. Then, for those that miss sessions, there will be some meat on the bones of their tales about what they have been doing while away from the group for a session.
<4. Open Table> Similar to Koch’s reassurance, you will have to place a heavy burden on the players to engage and use the available skills, like Cartographer, Survivalist, Pathfinder, etc. to solve difficult travel problems and get back to settled areas. Also, you can use remote villages or steadings as settled places with minimal services and accommodations available. Modify the Rites of Hospitality, or use whole cloth, to place one more test of Orator on the list of available skills for getting to a safe place at the end of a session. Additionally, warn players they might not complete a module in one session–I never saw a group of players (as GM nor as a player) resolve all the ‘rooms’ of an adventure in a single session.
<4. a. End of Session> I’m not certain what to say, but if you eliminate the given that characters start and end a session from town, you can simply start a session where things left off before. If someone shows up at a session in media res, maybe that’s a fair moment to pull out a table and determine how tough things have been for them to catch up with the group.
<4. b. Phases> Similar to a. If you eliminate the given return to safety, the phases remain a major milestone in progressing the adventure. Don’t skimp. Drive the characters through the process. Players can choose (mostly) whether to camp or head to town. Place that on their shoulders to choose.
<4. c. Town> Similar to a. If you eliminate the given return to safety, the town phase can be played in full. It is a valuable period of play, and you should not skimp on it. Drive the characters into the settled world and push them against the hard rules and laws, grind them against the market prices, fatten them up with a few free drinks and free meals, then gut them on the cost of lifestyle and taxes! Don’t skimp out on such a fun portion of the phases.
<4. d. Town Events> Well, play out the potential disasters during Town Phases. Don’t skip the phase.
<4. e. Money> Well, play it as written. It should cost much more than a minimum Ob 1 Resources test for most Town Phases. But, you can rig some visits to town without making a Town Phase of it. Also, using steadings or Rites of Hospitality offers alternatives to Resources tests that I found (as GM) entirely more satisfying and enjoyable than resolving things by Resources. It has a place, but it is better to keep the Resources tests in place for cities, towns, villages, and other big settled places. Just, if you use steadings or something like steadings (like maybe a way house), having those alternatives is quite a good method to introduce a price other than money.
Honestly, I disagree that TB is a good fit for a West Marches-style campaign. I think your bundle of questions illustrates many ways in which TB functions much differently and requires more investment or commitment from players in terms of time, effort, energy, attention, and attendance. It is not impossible, but there are issues to resolve. I feel it is best to remove elements of the West Marches in favor of TB as written rather than remove elements of TB to fit the West Marches.