Jim,
As you show your location as Huntingdon, you're not too far away from Grafham. As it boasts the largest UK fleet of Sprint 15s, someone must be able to help you, and you can see where they have placed their grippy tape (if at all - there are some Grafham Sprint 15 sailors who only sail unarig standard mode).
1 As far as grippy tape is concerned, you'll find that most people fit it on the side of the hulls, a little way below the deck so that when you hike you don't rub quite so much against the tape as you would if it were placed right up to the deck level. Also, you will be "standing" on the balls of your feet/toes, and you will only have (ends of) toes above deck level. Most of us seem to have bought tape from Steve Sawford (
www.speedysports.co.uk).
2 Try reading Mike Cemm's article "Sprint Sailing" in the Tips section of this site. It does cover getting in and out.
It implies you'll have your forward hand on the trapeze grab handle. I tend to hold the main and jib sheets in my front hand and the tiller extension (and maybe the traveller line) in my aft hand, and push out with no hand on the grab handle...... While the tiller extension slides through my aft hand, I can choose to do the same with the main sheet OR increase the tension in the main sheet as my weight goes outboard. I have the sheets and traveller line in hand to trim the sails immediately.
You need flexible legs to get the front foot on the hull side while being partly hiked out (bum over the side), and to get the rear foot on the hull side as soon as possible after you push out with the front foot so that you complete the manoeuvre. If this sounds illogical, remember that you are going out on the wire from behind the shroud; the trapeze wire will be pulling you forward as well as keeping you up (because it is attached to the mast - forward of the shroud at deck level); you use the front foot first so that you don't get pulled forward and dangle alongside the hull head first, and quickly bring in the aft foot so that you don't "fall" back alongside the hull feet first. You always need to brace against the forward pull, much more so when you are reaching and you trapeze further aft - from right at the back of the boat in strong winds.
I think most of us found getting out on the wire tricky at first - I found that previous crewing on a Dart 18 had helped.....