I have never seen a Standard in person. I have looked at ebay and it looks like it takes the same lenses and backs as the Universal and Super Press. In that case, you can use any of the ground glass backs. I think there were four; the gg only, the type that has the back fold up exposing the gg, and two types for single eye viewing, one I think with a magnifier.
I would suggest the type where the back comes up. They are more available and usually less expensive. The gg only is hard to find, even more so than the single eye types.
The 65mm lens is probably something like a 35mm lens on an 35mm camera. That was the first lens I got after I got the camera with a 100mm f/3.5. I really enjoyed it as it was wider than a normal lens, but I'm not a fan of 35mm lenses in 35mm cameras. Not wide enough. But when it is all you have, you like it.
The 50mm lens is more like a 24mm lens on a 35mm camera. If you want one, you just have to keep looking. I waited years for a 50mm lens to come along, and it was almost a give away. The 250mm was a long wait after that, and more expensive, but not what they seem to be going for now.
As to the 100mm f/2.8, I have never had one nor used one. Some people say they are very sharp. But the difference between f/3.5 and f/2.8 is negligible imho, and not worth the extra cost.
The extension tubes are easy enough to use. I think there are tables for them. There is also the possibility of using close up filters. Each solution for close ups has its advantages and disadvantages. Close up filters also have tables, but they are for use with 35mm cameras. I have never seen tables to use them on MF cameras. Regardless, for precise framing with either system, the gg will be necessary. I suppose you could use very careful measurements as well as calculations for exposure, and try to keep the camera pointed the way you want. I once did that hand-held with a Canonet just on a lark, and it worked surprisingly well with a close-up lens. I wouldn't want to try it with extension tubes.
