To record HD all you need is either P2 cards or a Firestore FS 100 720P@24P gives you 40 minutes on a single 16 GB card. Firestore offers great record lengths but caution needs to be used if you go with the firestore. To transfer footage to your computer you need nothing else. It becomes a workflow issue, there is no wear and tear on the camera if used since there are no moving parts. In the field if you need to be dumping cards and reusing them then you need something else or if you just never want to tie up the camera for this.
Old Mac Powerbooks have a slot for the card, newer MacBookPros you need an adapter. Panasonic makes P2 “decks” but they are pretty expensive. Hope this is a good start.
If you post your normal shot scenario it would be able to give better advice.