In the future, please read all of the stickies before posting.
The simple answers to your questions are:
Yes. Some testosterone will be converted to estrogen; if too much is converted (e.g. you have low cortisol, so your body is unable to utilize the extra testosterone and instead converts it to estrogen) then you may end up with typical high-estrogen side effects like gynecomastia.
The best way to avoid this is to monitor your estradiol levels (E2) and make sure that they do not become elevated. See the stickies for more information.
* 20 mg testosterone propionate
* 40 mg testosterone phenylpropionate
* 40 mg testosterone isocaproate
You might have better results from testosterone-cypionate or testosterone-enanthate. Regardless, increasing the frequency of injection is going to be your best bet - doing injections every 3 days (E3D) or every other day (EOD) provides you with a much more stable amount of testosterone in your system. See the stickies for more information.