With SEBLOD almost anything is possible, but if you want to get away from the standard operation you may have to dig into the PHP of the respective fields (stored in Joomla plugins folder).
Regarding the template calendar becoming huge - this is usually a template issue I think - first try with default Beez template (for example) in Joomla and see if it works. You can always just add some css overrides in your template to fix this I guess.