So, I need to go to two locations?
Depends on what you want, depends on whether you want to grind or play....
Basically, there's three different types of blueprint, which are give from three different types of location. Depending on what you want to build, you'll need to visit those. Depending on what your playmode is, you can relog on one location or visit another one if you want a second blueprint for the second device of the same type (e.g two different Guardian weapons require two weapons blueprints, but it doesn't matter whether you relog in one "weapons" location or fly over and visit another).
In addition to the blueprints, you also need Guardian materials and, in some cases, obelisk scans. The ED wiki has a pretty comprehensive overview (check under Guardian Broker), if you don't want to visit a broker and write them down yourself. Those you can get from either the blueprint sites or other guardian sites. If you're looking for clues, Canonn has written up and published more than you possibly could want to know in that regard, including maps of all the Guardian sites.
How do I know if I have enough materials to synthesize an SRV in case I lose one?
You can't synthesize an SRV, but as long as it hasn't blown up, you can repair it (RHS screen, Inventory -> Synthesis). The various possible repair levels also list the materials you need for that. Those you'll have to collect by shooting surface rocks on landable planets ("Prospecting"). Basic repairs (and SRV refuels - you're going to need a few of those) are done with low level materials that are available almost everywhere. But you'd have to be extremely careless (or inexperienced) to lose an SRV this way.
If I get killed is there a nearby station or will I have to make the trip again?
"Nearby" in ED is a very personal concept

. For some people, all Guardian sites are nearby to the Bubble. For everyone else, there's New Growth in Pencil Sector EL-Y d5.
This is the worst most confusing game design in any game that I have ever played.
Young people today... if you feel confused by this game, I'd recommend some of the old Infocomm adventures. HHGTTG was especially notorious in that respect
A game should be playable without YouTube and forums.
It is. But an open sandbox game in an arena this size will take a very long time if you want to experience all the niches without talking to other people. All the information you see on Youtube and websites has been collected by other players like you, playing the game. There is no (ok, with respect to the beta, very little) privileged information from FD - and they reputedly come down
very hard on anyone suspected of violating the TOS by e.g. disassembling the game files. Given enough time, you can do the same. Just keep in mind that all the data you can get through 3rd party websites is the result of three year's work of many hundred players, so I hope you don't have anything planned for next 50 years or so...
And items shouldn't be locked behind grind walls. They should be attainable through your preferred gameplay in time.
Nope - here I disagree. For one thing, the grind is in your mind. For another, why should, for example, someone playing as a trader, simply shipping medicine to outbreak systems, ever get access to advanced/experimental weapons systems - or need it?
Ok, I could imagine that experienced fighters (i.e. based on combat rank) might be able to buy (at an outrageous price) single pieces of those weapon systems, which would be lost upon ship destruction - if there was an adequate supply of the raw materials (i.e. Guardian scrap) provided by (other) players. But that would require another (parallel?) economic model, which simply isn't there (as far as I know - I don't work for FD) in the ED framework.