Please help me to spend my money !!!

Hi guys !

I really need to improve my search engine rankings.
Since i don't have time to read about SEO and i want fast results, i am willing to pay an expert to do the job.
I am interesting ONLY in White Hat SEO.

My plan is :
-To hire a guy to make some improvements on my side (forum/vbseo/tags/webmasters/whatever settings).
And after a while :
-To buy an advertising service. Backlinks, posts in Blogs/Forums/Social Networks etc...

Before opening a thread in the proper section, i am opening this one, in order to ask some things.
I am a noob on this area and it would better to learn the basics and not to waste my money.

Some questions about the SEO part :
1) What kind of access level, do i have to give to the guy i am going to hire ? Is it safe ?
- Access to my forum ?
- Access to my VBSEO panel ?
- Access to my google WebMasters tools ?
- Access to my google Analytics account ?
2) How fast will be the improvement to my search engine rankings ?
3) How can i be sure that a guy is really an expert ? Is there any way to prove me that he really improved some sites in the past ?
4) What would be a fair cost for his work ? Any suggestions ?
5) Is the SEO once for ever, or we have to keep making changes (and keep my forum up to date) every some months ?

And some questions about the advertisement part :
1) Are these advertising services really useful ? Or their posts will probably be deleted as spam from the forums/blogs staffers and i will lose my money ? Or any accounts they will create to advertise my forum will get banned...
2) For how long (approximately) will last the results of this advertisement ?
3) How can i calculate each one of the offers i am going to get ? Is there any safe way to chose the best option ?
4) A fair price ? Any suggestions ?

Some of my questions are probably stupid, but as i already mentioned i am not experienced at all on this area.

Thanks in advance for your help

Well I can try for some of the questions, hope this helps a bit.
1. Access levels
a. Theme -- if they change the theme, they will need access to it. Create a login for them then delete when done, or send them a copy of the site, they can make changes and send it back to you. Then check to make sure nothing was added. Odds are find someone reputable been doing this for a while nothing bad will happen. But do make a back up of site first and store in safe location!
b. vbseo panel -- no clue if they need it or not wouldnt think so, sorry i do wp, drupal, oscommerce etc.
c. you can upload a file and they can get stats from google webmaster no risk to you.
d. If they are a google engage partner, they can add your analytics into there site.

Improvements will most likely take some time to show.Ask for references and examples of work! Once your site is optimized, on site shouldnt need to be done monthly. Once in a while you might want to tweak stuff a bit, but not often.

Advertising is paid -- so your ads should not be removed during the time frame you run them. Posts may be used, and will stay forever if you do them right. As an example I have signatures in different forums that advertise some of my companies. All your ads should be tagged so you can calculate which ones work and which ones dont. And tweak each ad! Do split testing on every ad you can! Just some ideas , hope they help -- read a lot here to make sure your not getting ripped off too.

Thanks a lot tnhomestead !
Any other ideas guys ?

Up to the top !