Yep, those were made with a hacksaw. I actually do quite a bit of cutting with a hacksaw. If you have a good frame, and purchase good quality blades (I like Starrett - the yellow ones, 18 TPI) then you can make nice straight cuts, and pretty fast too in 1/8 to 1/4 thick steel which is the majority of what I'm using. The other benefit is it that adds to your days cardio minutes.
At first I was keeping a separate wheel for grinding just the tungston but then I started using whatever was handy and I haven't noticed any issues. When I start working with aluminum, then I'll probably have to be more careful about keeping things separate.
I've heard too that if you want to switch to aluminum with the same tungston, all you need to do is to strike an arc onto some copper for few seconds and let any impurities burn off before starting to weld on aluminum. Haven't welded any aluminum yet so I have no experience with this. I still plan to make the gas tank from aluminum so I will need to learn. I'm using the type of tungston that works for both carbon steel and aluminum so I might give this copper thing a try. The tungstons are not very expensive in the whole scheme of things so having dedicated ones is no big deal either.
The quickest way I've found to grind the tungston and get great results is to chuck the tungston into a battery powered drill. Then use this to spin the tungston, then while its spinning, move it against the grinding wheel. Fast and accurate. Arc from the tungston is nice and predictable.