You read that incorrectly (or maybe you read it correctly, but from a bad source). Resolution ALWAYS matters for print. Always.
Have you checked with your lab's website (or called them) to confirm that 300ppi is their recommendation?
No no no. Those options have NOTHING to do with cropping. You're reading those options from the Image Size dialog, and that has NOTHING to do with cropping.
Is this what you have? https://scontent-sea1-1.xx.fbcdn.net/v/t1.0-9/12960_10200455570738510_2011562893_n.jpg?oh=c8fd58cdd85605db892405e30d98aa79&oe=58E754BE
In Bridge, there are two ways to open a raw file. One is Cmd O (for "open") and the other is Cmd R (for "raw"). Can you try both, and make sure they both work? I'm suspicious that Cmd O might not work.
Textures are very easy to add. You'll be able to find heaps of them (both free and paid) by simply googling.
Then apply them to your photos using blend modes (and maybe masks) as I discussed in the Layers & Masks Class, of which I know you are already a member.
Oh, web???? Great! Just make it maybe 2000 pixels on the longest edge, then save as a jpeg. In the window there you choose the Quality level of the jpeg save, you'll see it gives you an estimate of the file size.