What is the recommended way to design a standee for print, in terms of dimensions? [duplicate]

Question

I need to design a standee 3x4 feet (36x48 inches at 300 DPI). The main element would be a 10-15 MB photo (4000x5000 pixel dimensions approx.) inside it and a text heading and 1-2 design elements.

The problem: When I create a document in either Photoshop or Illustrator for print (36x48 inches, 300 DPI), it is extremely slow in Photoshop. Illustrator still manages it but I also need a little Photoshop work.

The main problem occurs in Photoshop while creating any shape or writing text. It's very slow.

The confusion: Is it a right way to design at actual dimensions (say 36x48 inches instead of 12x16 inches inches)? Or most designers design at small size and later scale it up? (Unsolved)

Confusion 2: If I design at small size in Illustrator, but use the actual image, would scaling it up (until the image is not scaled up more than its original dimensions) for print give the same image quality, OR has it lost its quality already when scaled down (since text would create no problem, easily scalable)? (Unsolved)

Confusion 3: I need to save the work in PDF file. Now, if you design at small scale (say 12x16 inches instead of 36x48 inches) in Illustrator, is it possible to scale it up while saving as PDF (I couldn't find such option)? (Unsolved)

Confusion 4: It's possible to scale up the design in Illustrator (not sure about PDF). But there's no such option in Photoshop. Does it mean you should always design at actual dimensions in Photoshop? (Unsolved)

Confusion 5: If i place the assets in my laptop's SSD (currently in Hard Disk), would it increase design speed? (Unsolved)

My laptop specs: i7 8th Gen processor, 8GB RAM, NVIDIA 940MX GPU.

PS: I know there are too much confusions and queries, but I honestly couldn't find answers to these specific things. I believe all of them are somehow related. It might be very useful for future.

EDIT: I read 3-4 top answers on the question that is referred here, it helped me, but it solved another problem that is not directly asked in this question. My confusions are different, and still are not answered. I've edited the question detail wherever it was necessary to explain the confusions better. Please remove duplicate tag.

Answer 1

It's all about pixels :D

so basically you are creating 36 inch document with 300 DPI measn the document is sooooo big as 10800*14400 pixels and you definitily don't need to do it; the simple work around is your image is 4000 pixel long so use 120 DPI instead of 300 ; so your document will be now 36*120 = 4320 pixel long and this should reduce workload on photoshop;

Now main thing is scaling. so as long as you use shapes or texts (not rasters) no matter how big will you scale it; it'll be all same :D just keep in mind that if you scale then don't forget to cross check visuality of older and scaled on cuz sometimes effects can't be scaled XD

Answer 1 : No need to design in actual size if you know of your assets as resolution as i said below; just maintain aspect ratio

Answer 2 : illustrator works with vectors so as long as you draw anything in illustrator it can scaled to as biggest as you want but embedded image will lose it's quality :)

Answer 3 : just make your document at final resolution and then export it :) there might be workarounds too but i don't know it :)

Answer 4 : You can resize via Image Size option in photoshop and as long as you don't mess up with other things like resolutions and aspect ratios then resize works perfectly!

Answer 5 : Nope! SSD makes photoshop faster only if You use it as Scratch Disk and I strongly recommends you to use SSD as scratch Disk

And after all you have a nice PC so it shouldn't bother your photoshop :)