BAD GOUGE . . . do not ask about going to the VTU. The VTU is for people who are in the IRR, not SELRES. You're going to get some freaking weird looks at best if you show up as a brand-new SELRES asking to drop to the VTU. People who end up in the VTU are people who don't have the time commitment to be SELRES, but still want to accumulate retirement points. It's called the "VTU" because they don't get paid. Since they're IRR, they also don't have to do AT every year.
What you can do if you don't have a home is go to the unit that's generally next door to the VTU, the OSU or Operational Support Unit. The OSU is basically a catchall for people who are not assigned to one of the NOSC's local units. There are two people permanently assigned, an unrestricted line LCDR Officer-in-Charge and a unit Chief. You can ask to be assigned to the OSU in a status known as IAP or In Assignment Processing. This is a status that's designed for people either just showing up or who are between billets for various admin reasons. You get 90 days from the time you show up to find a home. This will give you a chance to actually learn the Reserves and pick people's brains.
There are two ways to get a home. A local fill, or being cross-assigned out. A local fill has nothing to do with where you live, but it's designed for people who are within driving distance of the unit. If you're a local fill, you are expected to be present for every one of the unit's drill periods, after traveling there on your own dime. Paying 100% out of pocket travel is the downside to a local fill. Oftentimes, as officers get more senior (by which I mean CDRs and CAPTs), this can eat into their drill pay. By regulation, the CO of a unit MUST be a local fill. But sometimes, hypothetically, the CO could live in Oregon and be slated to command a unit in San Diego. Tough luck; better get your frequent flyer miles. But as a local fill, you get your FITREP written by the CO of an operational unit.
Being cross-assigned out means that your TRUIC (training unit) is at one reserve center, and your UMUIC (mobilization unit; your actual billet) is at another. All cross-assigned out Sailors are entitled to what's known as IDTT (Inactive Duty Training Travel) once per quarter. That means the Navy will pay you travel and per diem to drill at your UMUIC. Your cross-assigned unit also owns your AT every year; you go where they say. Every other drill weekend, you have a choice. If you want to foot the bill, you can travel to your UMUIC on your own dime. Otherwise, you have the right to drill at your TRUIC as part of the OSU. OSUs (or at least my OSU) are essentially run by a pickup team of Officers, Chiefs, and First Classes who help the OIC and SEL create a more or less functioning military unit.
The downsides of being cross-assigned are that you need to be attached to a good unit who is willing to support cross-assigned Sailors. They're the redheaded stepchildren of the Navy Reserve. You can help this by footing your own bill for travel. This will get you face time with the CO and allow you to participate. Much as taking a non-local local fill, though, that may mean that you're essentially drilling for points only, because you're using your drill pay to pay for getting there and back. Conversely, if you're unemployed on the civ side, or need that drill money for your family, you can show up once a quarter. The downside there is the goodwill of your mobilization unit; you'll be the random person who shows up, eats a slot on their books, and doesn't contribute. Your FITREP will be a food fight between the OSU OIC or your cross-assigned CO, unless you're cross-assigned into a commissioned unit, such as a flying squadron. If you're attached to a commissioned unit, the unit CO will own paper on you even if you're cross-assigned in. This can be bad, because remember what I said about being the schmuck who shows up once a quarter? Congrats, you're now the cannon fodder for people who show up every day.
Additionally, you can end up in a unit where the OPSO or OSO don't understand how to manage funds. You'll put in a request for IDTT that quarter and get told "there's no money." First off, know that this is unadulterated bullshit; an OSO can go to Reserve Forces Command and ask them to pull funds from some other lazy schmuck who's not spending them. Second, you're kind of stuck if you're not in a position to make them understand that. In which case, you're stuck at the OSU. Which is OK for brief periods, but not necessarily career-enhancing.
