Many questions, you have a lot to learn. This is good that you are asking them. We all probably had questions when we started that we would cringe at now.
You have 002, an English yeast, this ferment best at temps around 65 F. If the temp is too high, it will throw off unwanted flavors.
Don't be too anal about following instructions to the letter. They are more guidelines to making a 'decent' beer, and some of them are not good advice. Don't fret exact temperatures, while sanitation is needed, being super clean is not a necessity, healthy yeast will cover a lot of sins.
The yeast pack is indeed pitchable. You would do better to make a starter, but for now, just pitch it. Don't worry about the temp. It could be pitched from fridge temp, but is better to warm up to room temp before pitching - exact temp is not critical. Pitching from room temp runs a risk of shocking the yeast and killing some cells. It will still work, but may take longer to show active fermentation. General recommendation is for yeast to be within 10 F of the wort you are pitching into.
Quick recommendation: Make sure wort is fully cooled before pitching yeast. Leave overnight if necessary to get down below 70 F before pitching yeast. Yes, I know there is concern leaving the wort for extended time. But .... if you pitch at 80 F, the yeast may start up while the temp is still around 75 F, and will not come down until active fermentation is done. Yeast generate a lot of heat during fermentation. Result = unwanted flavors; it will still be drinkable, it will still be beer, but will be much better if you had waited until the wort is below 70 F before pitching
Cooling wort (not the mash); it is generally accepted cooling down quickly is beneficial, as it drops proteins (helps clear the beer), and minimizes risk of contamination reproducing (120 F is a great incubator). However, many people do no cooling, and just pour the hot wort into the fermenter, seal it and let it cool for 24 hours before pitching yeast. very popular in Australia.
Adding Coffee. I just add whole beans a week before bottling. Whole beans is less mess and coffee readily gives up its flavors. there is no improvement with crushing the beans. I take the beans out of a fresh pack - no sanitizing; I expect them to already be OK straight from the pack. After all they were roasted and have no nutrients for bugs to work on. 2 to 4 ozs per 5 gallons.
Chocolate: I like using cocoa powder. Cheap non-brand is perfect. Don't use expensive cocoa, as it has stuff added to it. Unsweetened and Low fat (like 1%) is important. I use 8 ozs per 5 gallons. I put the cocoa in a large bowl, and slowly add water to it, need to add a little water and then mix, then add a little more, and mix, ...... and repeat until you get a slurry. 8 to 16 ozs of water should do it. I add a couple of ozs of sugar too to make sure the yeast attack it and disperse the chocolate. Heat to sanitize (boil in pot, or cover and zap in microwave). let cool a little and add. Adding at 100 to 120 F is not a problem, the small amount being added will have little affect on bulk temp. I would add to secondary, but can go in primary. Add after active fermentation subsides. Cocoa nibs are also popular - I've not tried them.
There is no Right way to do things. Many of us do things in different ways and get similar results.
Good luck with your brew.
