I am kind of new to Sysadmin stuff and servers, however I have some experience. I've already suffessfully set up my own server at Linode. (Now I'm planning to move to Digital Ocean.)

On the other hand, I just used the guides that are on these sites. For example: how to setup a LEPM stack on Ubuntu, etc. I've did that successfully, but my main challange here is, that I don't really know, how secure these installations are are what should I aim for if I want a server with the following specifics:

I will have a server with the following specifics:

2GBMemory
2 CoreProcessor
40GBSSD Disk
3TBTransfer

I want to host about -34 websites from these. These sites are getting a relatively low amount of traffic: about 10k visitors / month for all of them. On the other hand I want the servers to be lightning fast (I guess Nginx can help me out here). I am going to use it for Affiliate Marketing stuff and speed is the king there.

So I basically want a very fast loading server. Where should I get started? It's okay if I simply install LEMP stack on my server and run the sites from these? Do I need more configuration? Where can I get information about this? Are there any tutorials on this? Which peration system should I use?

Also, I couldn't see any in depth security tutorials that make it clear step by step what to do in order to protect the server from incoming attacks. The basic guides are fine for security - that I can find on Digitalocean's tutorials? Should I simply use cloudflare for security?

How should I get started to create this server or is there any guide to make it step by step?

Sorry if these are too newbie questions, I just want some resources that I can get started with.