The thing is, when you start the node it browses all stored files to refresh its databases and to know more or less precisely how much space is taken on your drive. In your case I assume it had no idea how much space was taken before browsing it all, because it had no previous data (as you had no more databases). This happens every time a node starts (or gets updated), whether or not your databases were lost or not, but it’s usually not a problem because while data is being browsed, the dashboard can display the previous state of the node, saved in the databases.
This browsing process can take a long time depending on the type of drive (CMR, SMR…), how much data it’s holding, its performance, etc. When I say a long time, my slowest node takes almost 30 hours to browse all of the 2TB of data it’s storing…
Having upload and download errors is not necessarily a problem because some of them fail “naturally” when you lose races against some other nodes that replied faster than you. In which case the download or upload is cancelled.
I’m not sure about the third one though 
@kevink saw the same thing there:
No definitive answer so far on what this error is about.
If these happen only time to time, if your node is getting ingress & egress and if your scores look and stay good (>95%), I wouldn’t worry too much about these.
In doubt, it doesn’t harm to run a full check on the disk to be sure it has no faulty sectors.