Should i focus spending my work points on my stats or save them for a promotion at my level? Is advancing to rank two a big upgrade?
I would definitely convert the stats, especially at your level, they will help you out alot.
Most definitely convert them for awhile. After a few days or a week even start saving them and see how it goes. If you think you are doing OK in saving them then continue, otherwise keep converting them. I personally would convert them like Koko said at your level.
is the promotiom worth 500 points though, i do engineering.
This is just my opinion on the matter.
I think the upgrade is definately worth it. You get more job points each hour worked. This is not a huge upgrade but...you will make up for "wasted time" saving points for the upgrade.
I would advance as far as you can and then use the points for stats.