Guild level: 80

Guild hall level: 1 - why? no need to spend the mega-pps considering what I use the hall for...

Decorations: nothing except a herd of veteran display cases for selling stuff at an incredibly discounted rate to the market (i.e., basically minimum 'tax / sales fees' on all my sales)

Usage: portals - to me it's all about speed, the faster I can pillage a dungeon, gate back to the hall, dump and stock the display cases then move on, the better

Hard to guild level 50? IMHO, I didn't find it hard at all to get to 50 - just lots of writs (mainly KY) and I make sure all groups do their HQs

I did find things slowed right down from about 60 onwards though - but I still stand by my recommendation made in either this post or another - keep at the KY writs - very fast turnover for very little running - even if you just set yourself 1hr every other night - the levels will tick over (slowly - but surely)