Trademarks are a 2 year process'es.
That's a bit on the high side. 13-18 months is a more accurate time frame to expect the approval process to be completed.
You'll need an attourney.
An attorney is not necessary. The application is not that complicated. There are services like LegalZoom that can handle the paperwork for anyone not comfortable doing themselves.
A finished product, that you will file with your application. The whole thing ends up costing about/around 10,000 $.
You don't actually have to submit a product. You can submit an image of the product, label, hangtag, marketing material, etc. Anything that shows the usage of the trademark.
Your trademark is only as strong as your sales.
This is not accurate at all. Some trademarks are not even product based, they can be service based. So the strength of ones trademark has nothing to do with sales.
In my opinion, the strength of ones trademark is their willingness to take legal action against infringement.
If your not selling out of state, then you have no protection out of state.
Again, this is not accurate.
You may be referring to common law trademark or state registrations. But federal trademark registrations have no restrictions based on what states you sell within.
And the only way to prove otherwise is SALES !!! SALES !!! SALES !!!
Actually, having a federally registered trademark is great proof of ownership. Sales doesn't mean anything. The first to register a mark will generally be granted ownership regardless of sales figures.