Tratan army, I don't speak German so I don't know! It sounds pretty similar. The Welsh alphabet is a, b, c, ch, d, dd, e, f, ff, g, ng, h, i, ll, m, n, o, p, ph, r, rh, s, t, th, u, w, y... all the double letters are actually one letter. For instance 'dd' is pronounced like the 'th' in The Rugby Forum.
One other belief about Welsh is that it is short on vowels, and for an English speaker scanning welsh words this might seem to be the case. But unlike in English the letters 'w' and 'y' are also vowels. W is pronounced like the 'oo' in too, and y is interchangable with u. So they are actually the same vowels as in English even though they're not represented by the same characters.
RC, your Welsh is coming on well, what you need is more experience of writing in it from day to day. It may be worth joining a welsh language forum like Maes-E.
Penodol - specific. So when I said 'Rho wybod os wyt ti eisiau gwybod unrhyw beth yn benodol RC' I meant 'Let me know if you want to know anything specific'!
'Gyda llaw' means 'by the way' or 'incidentally'. The literal translation is 'with hand', so maybe that's why you may have thought I could do sign language! I can't!
'Offer' - cynnig. So it's 'Diolch am gynnig i fy helpu i gyda fy Nghymraeg'. Watch out for the tricky mutation at the end there!
Welsh has always been a spoken language first, written language second, so you'll find that people write in a way that more closely mimics speech than the literary style. I speak with a thick north wales accent so my way of writing might be slightly different from someone in the south!
Diolch yn fawr am roi marc enw da (reputation) i fi, gyda llaw!