You have to find an attorney that you can work with. A deal at that size is large enough that minor mistakes could be really costly to you. I get that many attorney's have no clue about technology or the internet. I struggle with that myself. What I wind up doing is making sure they are a solid attorney, and I'll deal with specifics on the business -- basically explaining to them things I feel need to be in the agreement and let them figure out how to make it stick legally. I have directly been involved in a couple of asset purchases of my own companies/products. Not to the size you are talking, but I found I had to study terms a lot and push the attorney's pretty good, don't consider them the end all of knowledge, they are a tool to use. And I don't mean that disparagingly, just that they can never know every business or detail, it is our job to educate them and show them areas we have concerns and a good firm/attorney will figure out how to protect you.
You might be able to get some older sales/purchase documents online to use as examples of things to watch out for. I can share privately some of the "standard" clauses we had placed in our documents, but I really think you need a good attorney and CPA. As every deal is unique.
One other point, you can't stop them from using knowledge they gain from the due diligence part of the process. Yes you can put clauses in the letter of intent, agreement etc, but that just means you can sue them if you catch them later. Of course, they will claim they gained that knowledge independently and its hard to prove. This is why you limit the duration of due diligence. Keep it as short as possible so they have to act or leave, but not so short that you are unreasonable. Also, why I never had one, to me this is where a breakup fee may be worthwhile, make it painful for them not to complete the transaction, so that if they are just tire kicking to "learn" it still has costs.