The real question would be less of if Russia can settle it (since they can't until the railroads get set up to allow for it) and more of if Han settlement is affected in a significant way. Even when Manchuria was off limits to the Han Chinese (and also the Koreans, to a lesser extent), there was a significant amount of illegal squatting, imperial edicts on settlement (the Qianlong Emperor allowed drought-affected Han farmers to move east of Shanhai Pass), and immigration due to the regions you listed and the burgeoning Han population. It was already majority Han by the 1850s, as a result. Thus, the question is if Russia can actually prevent Han immigration into the region before they can actually start settling it.
At the time when Eastern-China RR had been built (1897 - 1903) as a de facto branch of the Trans Siberian RR (see the map below) it was too late even if Witte considered it as a tool for the potential peaceful acquisition of Manchuria: there were too many Chinese, mostly thanks to the railroad (by 1908 regional population grew from 8.5M to 15.8M due to migration from China). Russia simply could not beat that rate of migration.
On a purely political level, during the Boxer Rebellion Russia occupied North-Eastern provinces of China but the further steps did not happen due to the resistance of the former partners by anti-Boxer coalition. However, if we assume that everything worked out just fine and beyond the formal Russian goals (which amounted to getting a preferential status in the region) and there is no RJW, then Russian Empire ends up with an interesting demographic situation: in OTL excess of the population in Manchuria resulted in the Chinese migration (seasonal and permanent) into the Russian Pacific region because shortage of the “Russian” population was an obstacle to the regional development. In OP scenario Russia is getting between 8 and 15M Chinese subjects with a potential problem of controlling the new border because, taking into an account political situation in China, a continued flow of the immigrants can be expected. However, even if it stops at, say 10M, Russian Empire is getting a big minority group which is not easily mixing and this may (or may not) create problems in a future.
Now, taking into an account that acquisition of the region could happen only with an agreement of the other major powers, the OP scenario (with a different date) implies seriously different Russian-British and/or Russian-Japanese relations (probably Russian-American as well). Say, the British government (and public opinion) recognizes that Russian expansion in a region to which the GB can’t realistically get anyway is less dangerous to the British interests that a fast growth of the Japanese military and naval power while Japan makes an agreement with Russia by which it is getting Korea and some pieces of China including Port Arthur. Or pro-Russian GB does not provide Japan with the credits and technical help needed for war while the US remains neutral to those events.
Not sure if this would not require an intensive interference of the ASBs.