The Yashica has a light meter. It's often dismissed as rudimentary and in a way I suppose it is, but while I don't rely on it, I'm surprised how often I carefully meter with my LunaPro SBC then find the in camera meter in absolute agreement - this is with my 124; the 124G meter may be better. If you can find one, I prefer the 124 to the 124G. The "G" stands for "gold" and has gold plated flash contacts. The other external differences is that it's almost all black where the 124 has a fair amount of chrome. The 124 is said to be more rugged internally too - I'm not sure of that, I mainly just like the way mine looks. I got a nice Yashicamat 124 for $160 on eBay. You could list a WTB ad.
Handheld light meters, good ones, are very reliable. They do take a bit of learning to use. I use a LunaPro SBC. It, and the flash meter enabled brother the LunaPro F, are superb meters and commonly available used BUT - if you've never seen one they may be surprisingly big. There are certainly smaller meters around. You don't say what type of film but in practice, for something like street shooting with black and white or color neg, you can take a general meter reading for the prevailing light (a small pocket sized gray card is useful too,) set the camera for that, and shoot away as long as you don't move into widely different light.
Don't count on people not noticing what you are doing. Some won't while some will. People tend to mind a lot less, though.
Focusing at waist level is not something I'm comfortable doing with my Yashicamat 124, and I've never owned an autofocus camera except my little digisnapper. I use the magnifier in the Yashica and hold the camera up to my eye (but looking down) - then if wanted I can close the magnifier and compose from true waist level. Other than making use of the depth of field scale on the focus knob for zone focusing (so you set it to be in focus from infinity back to a certain distance, then be sure your subject is at least that far away - in good light with a wide range of focus this is a very fast way to work) I can't offer much more. This kind of street shooting isn't really my area.
The film doesn't load, wind and rewind quite like a 35mm. The Yashica anyway is slower to load. You get better at it (get a manual or download one if you get this camera) and it isn't really difficult, but it's not as quick as 35mm. The film comes on a spool. There are two spool slots in the camera, one for the film you are shooting and one for the take up spool it winds on. After your last shot you keep winding and that winds the rest of the film on the take up spool. You open the back, remove the spool, fold the paper leader down and there's a piece of "lick and stick" or other paper tape you use to tape the paper leader down. I forget which film brands have which of different types as they're all pretty obvious. For your next roll you move the spool the last roll came on over to the take up side and put the new roll in the film side.
Film winding with the Yashica may seem odd compared to 35mm but is easy and almost as quick. After winding the film leader onto the take up spool with the film crank it stops at the first frame. You then turn the crank a half turn backwards to cock the shutter and you're ready. After each shot you turn the crank a half turn until it stops, which winds the film, then turn it back a half turn to cock the shutter. Sounds odd but in practice is very fast.