These are 1" bars. You'll find them very difficult to deadlift with, because the plates are smaller and therefore you need to get way closer to the ground, putting yourself in an anatomically disadvantageous position. An olympic bar (2" diameter) is a much better investment. As you mentioned, plates are not all standard. There are 1" and 2".
The olympic set will be more costly, but it'll last forever if you take care of it. As for plates, anything under 35lbs is going to also put you too low on an olympic bar, unless you buy a few bumper plates which can ge purchased as low as 10lbs per plate. Then you can use smaller iron 2.5's, 5's, and 10's to continue loading the bar once it's the right height off the ground.
If you don't plan to deadlift and don't have a squat rack, or work on olympic lifts, a set of adjustable DB handles of any size will be totally sufficient. No bar necessary.