Should i use Google Verification & .. ?

[zipo]

Hi im a little new to all this -- here is my story - im running a forum & we recently changed providers. before we changed we were getting cached regualary(apprx every 5days) by google & the words from our index were comming up nicely in google searches BUT now that we changed providers google hasnt cached (or hasnt been able to) since 1st feb - i think it tried when we were down on the 22nd feb but failed coz we were not there. Ive recently added a site map so i hope that might help but im a little confused by a few things...

1. When i use google verification where (which folder) do i put the html file into ?& how does it work ?

2. When i add a site to google webmasters tools how do i know if its supposed to have WWW at the begining or not & will it make a difference to google bot if i add 2 sites , one with WWW at the front & one without ?

3. When i make a sitemap & if i have a forum would i start the sitemap from here 'www.site.com' or here 'www.site.com/forum/' & then which folder would i put it if were a forum

4. how long does google take to recache us now that we have been down for a while & why if we have been visted by google are we not cached ?

thx so much for any help im pulling my hair with all this right now

[zipo]

i have added a sitemap and google processed it ok but our site still has problems being cached in fact it recently reverted back to previous cache than the cache which i last saw there i think im doing eveything right & i never had any problems before we moved provider - our provider suggested that google may have cached our site incorrectly - Please can anyone help me