The Central Tool Co. micrometers are good ones, I used them for years, then got Mitutoyo. Also, I agree with the note about Joe Bergamo at Plaza Machinery. I have been in his place of business, bought from him with great results. He knows machine tools and parts very well. I would suggest a center gage, depth micrometer, good steel rules, a good bench or pedestal grinder with good wheels. I'm not real crazy about belt sanders for sharpening lathe tools although some really like them. As to tool bit sizes, your tool holders are probably made to use 3/8th inch. You can use smaller ones by using shims under them if there isn't enough adjustment in the height. Boring bars are available in many styles, you might go with the type that uses square tool bits to start with as they are less expensive than insert type.