The internet is a wunnerful (and slightly scary) place. The vast majority of people who claim not to be able to find what they're looking for are either 1) looking for something SOOOO obscure that there's just not much info available or 2) don't know how to construct an effective search string. Trust me, it's tricker than it looks sometimes. That said, you can google how to search for stuff (ironic, I know).
As far as actual sites I like for info, Wikipedia is a good starting point. As long as the article has plenty of references you can usually follow the subject off in plenty of ways and there's way more info there than people realise. Also IMFDB (International Movie Firearms Database) is pretty handy as it sets out to tell you what guns are used in what shows/films/video games. Not always a complete source but again, a very good starting point.
Forums are an odd one. You not only need to find one that isn't tied to a specific retailer or manufacturer (*cough*zero one*cough*) unless you're after specific info for that manufacturer. In addition foreign forums may have plenty of info but the recommended products may not be available where you are so could be of limited use. Once you've found a good forum, stick with it. People are notoriously cliquey online so sometimes you need to put up with a bit of grief before you're "accepted".
Youtube reviews are good if you want a lot of badly filmed opinions but there are some good channels out there too. A lot of tactical kit reviews from US users will be in respect of real guns and tactics so be wary of asking directly about airsoft as it can just open up a torrent of abuse. Equally steer WELL clear of making similar comments on blogs like Operator As Fuck as they will verbally eviscerate anyone that mentions the hobby! That said if you comment with respect and bear in mind that most of the OAF guys are actual serving or ex SF or PMCs there's plenty of very useful pictures of loadouts in action!