Why reply when you're clearly just guessing and haven't got a clue what you're talking about? With the exception of "South Wales" Shrewsbury guards never work to any of the places you've listed.
First of all, good luck!
At the moment, Shrewsbury is one big happy link of 36 conductors, so all conductors do everything (with the proviso that new conductors normally don't sign loco and stock for the first few months). The depot is currently undergoing a large expansion however, so how exactly the work is divided may change. At the moment they're the only depot that can work loco and stock South of Chester, but Cardiff are likely to take on some of that work soon when the Cardiff - Holyhead services to up to 3 trains per day.
At the moment, earliest start is around 0430 (first Llandrindod) and latest finish just after 0100 (last arrival from Wolves) although you may be required to work earlier/later then that as cross covering of Chester, Crewe and Machynlleth work (with the resulting taxis) is pretty common.
Fantastic bunch of folk working there, you'll have a great time if you're successful.