As an attorney who does this type of thing, I can comment on a few of these things:
1) 1x-2x multiplier isn't offbase historically. Remember, though, that not every niche brand can be maintained on a part-time basis without touching stock or things like that. So, when one thinks of, say, a 2x multiplier, the calculus on the part of the selling company is much different than yours (i.e. they are selling to cash in and avoid further expense, effort, etc..., as well as hedging risk, of course, which presumably is a goal you share). But it doesn't necessarily impact the acquiror's calculus - depending on the type of buyer, they are going to fit your brand into their existing sales infrastructure. So, the effort and expense you incur doesn't matter to them quite as much as you would think.
In other words, you might not be able to reasonably expect a much greater multiplier because this business is so easily self-maintaining. Instead, it might just not make sense for you to sell.
Mind you, this is assuming the acquiror has an infrastructure your brand would fit into. Other types of buyers may feel quite differently and could pay a hefty premium for a business like yours. Finding that type of buyer is something I'm not sure how to do.
2) How these transactions are structured depends in a large part on the type of buyer. And there are a lot more structuring variables than all cash vs. financing.
3) Tax perspective? Not sure how you are structured right now. You may be able to qualify for QSB treatment, which would exempt much sale value from capital gains taxation. But I'm not sure you are structured now to allow that (or if you are an entity at all). There are way too many variables in terms of tax implications and you just need to make sure you have an experienced tax attorney (or accountant, if they have the right experience) looking at your proposed deal structure and working with the main attorney representing you.
4) In terms of the type of lawyer, an experienced corporate and commercial business attorney makes sense. This is not the size of deal that would be cost effective at a large firm. So, maybe I'm biased given what I do, but I think you'd be looking for a smaller firm that has business M&A experience. PLEASE make sure you go to an attorney before you sign a term sheet. You'll have a much harder time negotiating things if you haven't done so at the term sheet stage.
Hope this is helpful and happy to answer other questions.