A drill bit will not get your broken tap out. You will have to use a chisel or a center punch to try and break it up into pieces and pick them out or push them through the hole. A bit will just break making your problem worse..
ANS 2 - I've done this many times with right angle pliers. I have 3 sizes of needle -nose pliers that turn a right angle about 1/2 -1 inch from the point. These are available in real tool stores. Take the appropriate size plier and carefully fit the points around the tap and gently rotate anti-clockwise while pulling up gently too.
Your meaning is not clear. - If you are going to tap the threads in, use a 7/32 drill bit. If you want a hole that this bolt will slip through, use a 9/32 drill bit.
Use 7/64 as tap drill and 9/64 as clearance drill
Not unless it was reasonably loose. Usually when faced with this, I drill into the bolt with a very hard drill bit a tiny bit thinner than the bolt - ie if it's a 3/8 bolt, I drill in first with a 1/8 drill to create a guide hole, then after with a 5/16 drill to cut right through, yet not harm the threads. You have to be very careful to stick to an exactly straight course. After the hole is cleared, I pull the threads left from the bolt out as far as I can, then use a 'clearance' tap of bolt size to re-tap the hole.
Your meaning is not clear . -If you are going to tap an M5 thread, then use a 5/32 drill bit. If you want a hole that an M5 bolt will fit through, use a 7/32drill bit.
I would use an 18mm or 23/32 drill bit, in general, although it does partly depend on the thread type ( UNF, UNC etc) and the material .
I use a 3/8 bit for tapping fine thread, or a 11/32 for coarse threads.
The best way is to use a drill bit for metal and drill a small hole in the bolt. then use an extractor to back the broken bolt out.
You drill the bolt out that is snapped off in the engine,with drill bit made to drill through metal. Then use a thread maker,tap. Auto parts stores carry these. I no u can get at autozone. The tap makes new threads.
Remove the broken bolt and replace it with a new one. There are several ways to remove that broken bolt. You can remove the valve cover and weld a nut to what is left of the bolt, wait for it to cool off then unthread the broken bolt. You can also drill out the center of the broken bolt and use an easy-out. You can also drill into the broken bolt with a left handed drill bit, sometimes the drill bit will catch and spin out the broken piece. I would go with the first suggestion.
Use a standard HSS drill bit, but slow down rotation to about 500 rpm.
In engineering you can use items around the workshop such as posters on info boards or their may already be drill and hole sizes for tap for example a 6.8mm drill bit for a M8 tap on a technical drawing or bend tolerences for the materials thickness.
You need a diamond tipped drill bit to drill glass or tile.