From the different operators in Kyrgyzstan, Megacom has good reach, low prices, the best speed and good customer support. Beeline comes in second place. Roaming should work with your foreign sim card.
Opensignal app has a map of the reach of each network, while the prepaid data sim card wiki has more information on buying sim cards.
Internet
Mobile internet is inexpensive and fast enough to do research and stay in touch with people. 3G is available in the major towns.
Bishkek has plenty of coffee places with wi-fi and your accommodation should have decent wi-fi too. Internet cafes still exist as dark holes filled with gaming teenage boys.
There are few restrictions on the internet in Kyrgyzstan. Only a few political websites are blocked; the government does not have the resources for a comprehensive internet filter. Only Silicon Valley and various foreign governments are monitoring your online behaviour.