Swings and roundabouts - My mortgage is with Bank of Scotland, and I've had prompt, friendly and courteous service every time I've needed to call them!
I also bank with HSBC - have no complaints whatsoever, I'd highly recommend them.
Your specific queries
1. Personal banking has very few 'fees' as such, the UK's banking system is quite different from the US. I don't think you need to base your bank choosing criteria on the basis of fees (check of course OverDraft fees, and letter writing fees whilst in OD, charges if in OD etc etc, just in case, there will be variances between banks, but vastly different)
2. I don't think theres any one bank that builds credit 'quicker' than any other. I may be wrong on this, so far I haven't heard anything to suggest it. Usual things apply, pay all bills on time, try to stay out of OD etc and you should start to see a build up. I remember when I asked for my Business Bank A/C with HSBC, I was shown my application and the quick once over of my history with them showed me a score of something 78. When I asked if that was '%' she said no, its a very high score and shows me that you will have no problems with getting the business account, in fact the max number was something 87 or something. See if you can ask you're bank something like this periodically to see if you are 'gaining'
3. Most banks here will have higher charges to Xfer amounts to the US than compared to specialist money transfer organisations. I've read a few posts on here about people using XE.com . Paypal is an easy way to achieve this as well, although look into their charges. I'm sure there's others, ones that spring into my mind are the people who deal in international property - but they usually require quite large amounts to get good rates - no harm in finding out though!
Hope this helps!
Cheers !Dennis! West London & Slough UK!