Dried tomatoes vs. dried tomatoes in oil

If you are really set on doing this, just use the same amount by weight or volume, preferably peeling the tomatoes first. (Cut an x in the bottom, dip in boiling water for 10 seconds, pull off the peel). You'll have plenty of liquid coming out of the tomato, don't worry about that. But honestly, I don't recommend doing this. Fresh tomatoes that are any good are so good uncooked that it is a waste, and fresh tomatoes that aren't good won't get better by cooking them. Even Mario Batali says you should use canned tomatoes for cooked sauces.

There is no exact conversion because there are so many different varieties of chickpeas or any bean types for that matter

Their water absorption rate and amount is effected by many things including how they have been stored, have they been heat treated on import, and what time of year they where grown!

My rough rule of thumb for beans in general is 2.5 ±.5 times the volume and 2 ±.5 the weight after an overnight soak

With our local chickpeas it's 2.2 times the weight after 10 hours at 20°C (on the bench)

200g should be around 440g of soaked chickpeas. 1 cup of chickpeas is around 240g, so just shy of two cups of soaked chickpeas should do it