Secondly...listen to these guys on here, they know their stuff!!
Read, read, read and research everything before you buy it or take any steps.
Make sure you understand how to cycle your tank.
Plan ahead for your ultimate goal...what would you like in your tank?
If your LFS
gives you any advice, say thank you, come home, and check on here before believing it.
What do you get in the plug and play? I got a semi plug and play and ended up replacing a lot of the things that came as part of the package because it wasn't good enough quality.
eg. the lights weren't suitable for keeping the corals i wanted. the filter is not needed once your tank is cycled as your LR
becomes the filter so i got rid of this and replaced it with a new powerhead to create flow.
Salt mixes are salt mixes. I think you should find one you like and stick with it. You get what you pay for, with all things, so buy the best quality you can.
Patience is what you need and will slowly drive you insane...but it's worth it in the end.
Im still very new to all this too and you will get much better advice than this however hopefully this will start you off.