Try auctiva or something similar to help with listing. With services like this, you can schedule listings for free, so you can do the work whenever you like, and get them all starting on Thursday evenings for 10 days.
If you are organised, it doesn't matter how many auctions you have finishing at once. I have 100's finishing every week at the moment, without too many problems. I have a 'filing' system in my email - awaiting payment, awaiting wrapping, awaiting posting, and the items get moved through as they progress.
Taking Paypal does help speed things up. I don't like the extra fees, but hate the faff of cheques and waiting for payment to arrive.
Every time I do a run to the PO, I email the buyer to tell them their item has been sent, and update the 'my ebay' section to show it's been sent, so I can keep track of everything.
I have found average prices for my items have increased since I started using Auctiva as you can include as many photos as you like for free. Photos are much better than descriptions IMO.
Offer lots of postage options - if you can courier, then people could potentially buy lots of things, and only pay £4.99 P&P. I always say on my listings that the maximum P&P I will charge is £6.99 regardless of number of items won (providing I can get them all in a box). I also state that people are welcome to collect in person. I think it makes everything seem more genuine, and also local people bid as they will save on P&P, which pushes up overall prices. Remember to list your cheapest P&P option first, as that is the one that shows up in the search.