1) You can get a tourist visa to visit her and your Chinese friends, but the invitation letter from her and the copy of her passport or ID card is required to send to you
2)after marriage, you can apply for tourist visa for family visit at the local Exit & Enter Department of Public Security Bureau, maybe you can get one year residence permit or just 6 months L visa. Generally speaking, it is hard to get one year residence permit for the first or second time application. If you have live in China for one year, maybe you have chance to get one year Residence Permit. The best way is to find a job in China, go to Sri Lanka to apply for work visa, then return to China to apply for residence permit. work visa holders should apply for residence permit within 30 days after entry.