How soon after a chemical pregnancy can I ovulate?

Soon. If you have passed your pregnancy, you may ovulate within a month.
Varies. It's impossible to know for sure, but since most chemical pregnancies involve bleeding right around the time of normal menstruation it is entirely possible that your cycle will continue as normal and you will ovulate around the same time you usually do. Again, exact timing will vary depending on circumstances and individual cycle differences, but ovulation as usual is definitely possible.
Ovulation after +hCG. Assuming that you are pregnant ovulation will be delayed until at least 10 mos. If you mean + ovulation test the answer is 24-48 hrs depending upon the sensitivity of the test and your body's own cycle.
2 weeks. My assumption is that you were pregnant with a very low hcg titer and experienced a miscarriage. The day that you started bleeding, i.e., having the miscarriage, would be the first day of your new menstrual cycle. If you typically have 28 day cycles, you would ovulate after 2 weeks.