After 250 prints, you ought to be well on your way to being a darn fine printer! 5x7 works as well as anything: for 35mm I rarely print any larger as my pictures seem to fall apart if I go much larger than about 6" x 8". It's a personal preference thing: I've never cared for mural sized prints.

Dektol is a perfectly good print developer. Personally, I'd go with whatever is easy for you to get. In my area, everyone carries Kodak chemistry so that's what I use. If they carried Ilford, I'd use that. It's more a matter of learning to use it than of being these huge differences between chemicals.

For prints, there's no reason why you can't use tongs to handle the prints. I like cheap bamboo tongs; they're also made in plastic and stainless steel. I believe that my bamboo tongs cost less than $4 for a set of 2 (one for developer, one for stop and fixer.) You don't need to touch the chemicals at all and with reasonable ventilation you won't be breathing it, either. Using nitrile gloves for backup and a plastic apron to keep splashes off your clothes and you ought to be nearly impervious. Standing beside your man as he does the dirty work -- priceless! Don't forget to scan & post pictures for us, too!