Scotland does get more, because the Scottish population used to be a bigger proportion of the UK population. The formula now used only considers the population change for increases/decreases to the yearly budget, so a budget increase/decrease will be in proportion to the current population levels, but not the amount carried forward from the previous year.
Scottish GDP per-capita (per-head) is lower then the English GDP per-capita, however, that does not include the gas and oil fields. Depending on how they'd be split up between England and Scotland, the Scottish GDP would increase to higher then most regions of England (probably all except for London and the South-East) with oil and gas included (because Scotland has a much smaller population, a decent amount from the gas and oil fields increases the GDP per-capita far more then it does for England).
However, I do remember it being calculated somewhere that the amount extra that Scotland has received over the years does outweigh the extra revenue from oil and gas.
England would get a share of North sea oil? Again, politics and geography are by far my worst subjects, so I'd need someone to explain why England would get any of that resource.