hi,
Great work on the basics. The patience you have to do these drills will pay off for sure

I am a newbie on here too and these are suggestions that I got from the forum and helped me a lot for practise.
Firstly, please get the x height larger. 3 mm is too small to focus on the shape. A good size to start will be at least 6mm x height.
Again start of with a 2:1:2 ratio so that the stroke formation is comfortable. Making longer strokes for ascenders and descenders will help in practise. Once there is control on the pen and pressure the sizes and ratios can be varied.
getting to your queries:
1) the dreaded "o" and ovals

Yes its supposed to be long and thin. Typically the total width of the letter should be ½ the height. so 6mm x height means a 3mm width of the letter.
You have two places you can start. The way you have mentioned is one. The other is'
Start about ¼ way down on the far right. Move pen up with no pressure forming the top of the "o",
continue the shape on the left side, slowly increasing pressure till about ½ way down
Start releasing pressure and have no pressure by the time you reach the bottom.
Continue up to join where you started.
I find this give a better thin thick progression. The additional dot where the connector goes is the second stroke. Separate from the Oval forming stroke.
The reason letters tend to look fat is due to ratio of height to width. This must be ½ or less. You can make guidelines that give you slants more closely placed (at ½ x height). I have explained the process to get that in this thread
http://theflourishforum.com/forum/index.php?topic=3322.msg45957#msg45957 (reply#4)
Hope this is helpful..
Great work so far, particularly the bird flourish. Love that
Happy writing
-Prasad