Yes, you can negotiate with the IRS directly without the help of a professional. However, this doesn't mean it's a good idea. The tax collection laws are complex and a professional can save you time and money.
If you manage to make it through the collection statue of limitations (10 years), your debt will be forgiven. Other ways, like negotiating an Offer in Compromise, will most certainly require the help of an expert.
Most of the time, yes. However, the statue of limitations can be extended due to filing bankruptcy or other types of tax appeals.
The IRS will accept any payment you are willing to make, and there is no minimum payment requirement to make.
You must go through a process called penalty abatement in order to get IRS penalties waived. It's recommended that you speak to a professional, as most people don't have a valid reason for accruing tax debt.