So could anyone help me out and give any advice on my scenario?
You can buy accounts if you trust the user who is selling those accounts and if you have doubts, it's better to earn activity points on you own. There is no limit on posting any threads or making any comments. Read this:
https://bitcointalk.org/index.php?topic=178608.0And what is the some of the better if not best signature company to use?
Any signature campaign that has an escrow is trusted.
I see so many and I dont even know how to sign up, I dont know how to attach my BTC address to my account, etc.
You need to go to your profile:
https://bitcointalk.org/index.php?action=profile;u=821174 and you can select Forum settings where you can find an option to add your bitcoin address.