business visa is a good move, but 30 days should be enough time (a week to Irkustk, another two weeks to Moscow, it takes a day to ride from Moscow to any Eastern border (a long day.......)
Russia rocks, have a fantastic time!
p.s The roads in Russia are pretty good compared to a lot of the former USSR but beware trucks being overtaken by buses coming towards you - you are expected to leave the road (happened twice)! Also people flashing you normally means cops ahead. I got stopped a LOT, 95% of the time smiles, handshakes and lots of 'I don't speak Russian' if they are moving towards a bribe should see you through