The plates are with the shoes. or should be.

the plate normally comes with the shoe. There are two main types of shoe plate - road (3 fixings for Look / SPD SL) and MTB (2 fixings for SPD / Crank Bros etc.)

The nut plates were included in my shoes but when I bought the cleats they also had the nut plates so no need to buy new ones.

they did include the plates, but I didn't need them for the dhb MTB shoes...

DHB M1's come with nut plates.

The cleats also come with nut plates.

I have DHB M1 shoes and these cleat have all fittings etc to attach. You will need an allen/hex key.

No, the plates should be in the shoe.

I bought the 51 cleats and yes they came with shoe plates

Yes

Yes, they do

Yes - they do!

Just bought some, and yes they do.

Yes, however they are the type that will release with multiple direction heel movement - not just the horizontal release. Because spin class will simulate hill climbing, these particular cleats can release with upward heel draw. Check the other 2 cleats if you're concerned about your heel disengaging on the 'hill tracks'.
Hope this helps!

You'd need to ask at your spinning class as they might not have the standard pedals fitted. Your instructor should know.

The cleats I have came with backing plates (cleats arrived screwed into backing plates). The shoes I have say that you can pull out the insole from the shoe to access the backing plate. The backing plate should just come out of the shoe, providing the cleat is undone already.

Cleat sets come with new threaded anchor plates, if your shoes need a special plate tese may not fit though?

Not sure about scott shoes or spinning, but they work with specialised shoes. I reckon on them being standard.

Hi there, you don't get cleats with shoes, they tend to come with pedals. I'd advise the multi release cleats for starters as there's less chance of you keeling over by mistake. some of Shimanos one sided pedals actually come with multi release cleats as standard so you get to save some dosh

Standard release is ankle twist outwards. Multi release is twist out or in or up and out. If you are planning jumps multi release are no good.

Multi release a great for newbies to clipless and also for more interesting XC terrain where you may need to release quickly. For example going uphill and hitting a boggy spot. No release means an unpleasant stop at the end of the fall so its important to be able to release.

Not sure about shoes but normally road shoes have a different set up.

Either SH51 or SH56. SH 56 are multi release and SH51 single. Multi release in my opinion are better for true XC MTB but no good for jumps etc.

no, you need crank brothers cleats, though they fit the same fixing on the shoe.