Grease = copper grease ONLY.
Pistons will push back easier if you release the bleed nipple a little; you will need to bleed anyway so have the bleed kit ready to go.
I've always found it easiest to push them back with a screwdriver levered against the pads, which releases the pads at the same time. Pistons must be pushed back square-on, if they're not moving then you're doing something wrong, start over.
Are there anti-squeal shims? Don't assume the originals are the right way round, monkey+spanner: they have to go the right way round; this is where a light smear of copper-ease goes.
Clean everything out. Thoroughly. Examine piston and seals.
If the pad don't fit scrape paint off its sides esp pattern part ones; OEM should fit perfectly; do not penny-pinch on brake parts.
Plumbers wrench = C-jaw gas pliers? - use them agains the pad and cylinder not the piston itself.
Brake cleaner spray.
Fresh brake fluid to bleed with.
For a DIY job at roadside I'd allow 2 hours: it may take 10 minutes just to get the wheel off.
10 min to get the pads out
10 min to get the disc off
20 min to clean everything
5 min to put the disc on
5 min to put the disc on the right way
10 min to insert and align pads.
20 min to reassemble and bleed.
10 min to find the long socket handle to tighten the wheel nuts
30 minutes to clean up.
That's 2 hours of my time and the garage does it far quicker and charges relatively little.
Me, I'm a physicist-engineer not a spanner monkey, been there rebuilt engines you name it done that, boring: I get dermatitis.