I couldn't find any firm answer in rulesbook, so i post this question here:
Is purhasing technology obligatory to draw additional, 2nd Event card during this order?
After studying descripion of Research order in rulesbook I think it is possible (and powerfull) to execute the order in this way:
1) Draw Event Card (required)
2) Draw 3 Comabt Cards (optional)
3) Purhase technology (optional)
4) Draw another Event Card (optional)
However, some people who play SC with me state it's not true and it would make the order even too powerfull. For me, it's balanced ability, but buying technology each time makes it really hard to exploit efficiently.