(1)  That's a hard question too answer, it will depend on how much you cut and what different types of vinyl you use, some vinyls are harder than others and therefore will dull the blade quicker than softer vinyls would. Just cutting plain vinyl the blade will last a lot longer than cutting tougher stuff like metallic vinyl. Purchase a 60 degree CleanCut blade now and use it, keep your old blade just for cutting metallic vinyl that way you're not shortening the life of your CleanCut blade.

(2)  The only difference there is it will be stronger but there's no need another unless something happens to your other holder

(3)  Buy a 60 degree CleanCut blade and that will cut everything you need, there's no need for any other angle, that will be all you'll ever need.  The CleanCut blade will out perform all other blades and remember to back the pressure off before using it or you could damage the tip. You should also have spare in case you accidentally damage the blade you're using.

Joe

60 degree CleanCut blade is all I use in my Graphtec and Roland also!

strongly agress

I'd invest in a better holder before allocating almost the same amount on a single blade, but that's just my opinion. If you can swing it, get both like the rest of the pack. I've not felt the need to "upgrade" my blade since getting the new higher end holder for my old CR630 pcut. As you too will find, the plastic holder is pretty crappy compared to the upgraded all metal magnetic variety.
I normally use my plotter for larger signage so standard 60 degree carbon blades are all I ever use. As for blade life, I have to guesstimate that I've cut at least a couple of miles of assorted vinyls while going through only three blades (not counting one dropped and one lost blade) in almost four years.
You'll know when you break a tip because the blade will begin to scratch and/or lift the vinyl.

That's what this community is about helping each other be successful 

yup that is what I use for my reflective blade

I have Roland and Mimaki holders now (from China) pretty good quality Holder and 1 blade for $40.

Be careful with the chinese "Graphtec" holders, I wouldn't sell the ones I have seen.  Even from the company I get the Roland holders from.  I am making them remake them to my specs.  Do not know when they will be available though.

Ross