IIRC is there not an example of a TNG-era escape pod in the TNG Tech Manual? Much more cubic-shaped than the First Contact
type. I would imagine those small types would have been abundant in the Wolf 359 battlefield, maybe with a smattering of the newer ones that have been ejected from newer ships.
Consider also the escape pod used by Sisko in "Emissary" that was attached to the Miranda-class Saratoga
- no clear shot of the outside but I got the impression it resembled a shuttlepod with simple thrusters. Shuttles themselves could also have been used as lifeboats (cf. Star Trek
In terms of how the shuttles are recovered by ships, Holdfast
has already mentioned tractor beams and their own thruster power. Depending on how safe the battlefield was to enter afterwards (lots of debris drifting around), survivors may also have just been beamed onto ships en masse
(consider Ezri's recovery of Worf in "Penumbra").
I imagine the survivors of Wolf 359 would have done that sort of thing almost immediately as they might not know how long they'd be bobbing around for waiting for rescue.