Can we convert all deski reports to webi reports in one go ?

Hi All , As we are prepping up to upgrade from BO 3.1 to 4.3 via 4.2 through RCT, one of the dependencies was to convert all deski to webi reports ? we have close to 800 deski reports. Please if you can share your expertise on following queries , it will be of great help.

1.Can we convert all 800 deski to webi reports in one go ? or is there a limit in number of reports that we can upload for conversion in a single request ?

2. If few reports fail to convert , would it ideal to directly rebuilt the report from the scratch ?

3. Plan is to convert all these deski to webi in 3.1 and them move to 4.2 version. Is this an ideal approach or should be the other way around, migrate the deski reports to 4.2(if it allows) and convert them to webi on 4.2 ?

Kindly assist