I'm pretty naive and new to all of this legal stuff and it seems like I'm learning the hard way about all of it. I signed a confidentiality/non-compete/non-solicitation at a previous employer, and was recently offered an internship (not done school yet) at a large tech company. I disclosed those previous agreements to them and they seemed pretty sketched out about it. They wanted copies of said agreements and to know generally what I did at previous employer. Is this standard procedure for big companies? Is there any chance that this could ruin my job offer? The two jobs are totally unrelated. I just want to make sure that these previous agreements aren't going to mess up my opportunity in anyway, as it is super important.
No one can give you a definitive answer without reading the full text of the documents you signed. If this became a big enough issue you might want to talk to a lawyer.
That said: In general, an NDA should not stop you from getting a new job. When you signed the NDA you promised not to disclose certain types of information about the company. So it shouldn't matter where you go to work after that, as long as you don't disclose this information. Unless your new employer is hiring you with the thought that you will tell them all this secret information about a competitor, it should be a non-issue.
A non-compete agreement is a different thing. By definition it limits where you can go to work after leaving the company you signed the agreement with. I once had an employer ask me to sign a non-compete agreement that said I would not take a job with any company that had "anything to do with computers of any sort whatsoever" for two years. That's pretty broad to begin with, probably eliminating about 90% of the companies in the country. Considering that my profession is software development, that basically said that I wasn't allowed to have a job for 2 years after leaving them. I talked to my boss and got them to change "of any sort whatsoever" to "relevant to the business of" that company. But I'm sure lots of people take jobs without even think about the non-compete agreement, then on their first day they're given this form to sign and what are they going to do? Refuse to sign and maybe be told, "Oh well then, I guess we have to withdraw the job offer." And you've already quit your previous job, maybe turned down other offers, and you're in the street.
Anyway, my point is, you should ask to see any non-compete agreement before you take a job. But given that you either didn't do that or found it acceptable, now the issue is to analyze whether the terms of that agreement prevent you from working for this new company. If they do, then you're pretty much out of luck. Find a job that you can take without breaking a contract. If they don't, then no problem.
In real life, I don't recall a company ever asking me if I had signed a non-compete agreement that would prevent me from working for them. I think that generally companies don't worry about this sort of thing unless you really cause them trouble, like stealing clients from the former company, or starting up a project that directly competes with a project you were involved in at the former company.
This is perfectly normal. If you signed an agreement with Burger King, and then went off to work for MacDonald's - it's possible that your new employer could face legal repercussions.
The new company wants to make sure that they're not going to get sued for hiring you. If the two companies are completely unrelated, you don't have anything to worry about. The company is just doing due diligence.
NDAs are important. They can bring both you and the company you work for into serious legal trouble if you are hired in violation of one.
It was good to bring it up ahead of time, since it's not necessarily easy to trace down, and it's much better for the company to research it first, than for you to be terminated abruptly some number of years or months from now when the company figures out they are in violation and tries to fix the problem as quickly as possible.
As to what happens in this particular situation - this falls into the realm of "get a lawyer for advice" - the writing of this particular NDA and the way it's interpreted by the new company's lawyers is the key to the likely outcome. Some NDAs have been ruled unenforceable by courts, and some have led to years of legal battles. Some companies are super cautious, some are not.