Leszi, welcome.
Questions like yours are often asked - so you will likely get many opinions.

I would suggest that you consider the sensor as identical an all the following T2i(550d), T3i(600d), 60D, 7D, (the T4i has a small updated for the video folks). Not being a 60d experienced perhaps someone can provide an thoughtful comparison of the feature upgrade for your topics of interest between the T2i/T3i and the 60d. For Macro work the tilt screen is indeed handy and it is on T3i/T4i and 60d.

I think most folks would confirm - it is more about the glass than the body, particularly when you have selected the sensor version. The "regular" canon macro from all accounts really is very nice.

Lens selection - many people, including myself, have walked through the 18-55/55-250 to either the 15-85/17-55 on the short end and the 70-300 "or L better" on the long end. The 18-200 should also be considered, I found that the break point at 55 mm was very inconvenient. The 15-85 has some macro capability.

As for the speedlite - consider a YN 565 - with T3i/60d/T4i/ you can use it as a slave as the pop up flash serves as the master and there is a lot of lighting options available to you. Very powerful and feature rich flash for less/same as the canon.

Welcome to the amazing world of digital photo - the most important thing is to enjoy it.

Mike