1) if it is a thoroughbred core, it will run hotter than a barton. Although not out of spec, idle temps that high would bother me. I would invest in more/better ventilation. Are you using the stock cooler?
2) I would say it is better to run the ram synced
*edit* If it is a tbred core, you can probably run the mem synced and *IF* you get your temps straightened out, bump the FSB up a bit.
I would be more concerned for your HD's - at 50oC you start to risk destorying them - check your temp reporting software and see if it reports temps on the HD(s) - mine does and it is worth cross checking against mobo temps, they can vary quite a bit if mobo reports from NB site.