Both have arisen because of devolution.
The �West Lothian question� (why Scottish, Welsh and Northern Irish MPs can vote on matters which do not affect their constituents) was foreseen and raised well in advance of the 1998 Scottish devolution (as early as 1977, in fact, when devolution was first seriously considered).
The Scottish parliament has control over a large number of matters and does not need to seek agreement from the Westminster parliament to implement measures which only affect Scottish residents. English MPs have no similar luxury for matters only affecting the English and can (and often are) outvoted by MPs from other parts of the Union
As with most things it was dismissed out of hand in the run up to devolution, but is now proving to be more and more relevant as Scottish, Welsh and Irish MPs look after their own conststuents but also have the right to vote on purely English matters.
The Barnett formula was introduced around the same time to determine how much public expenditure each of the constituent countries of the Union would receive. Last year Scotland received 97% of the average per head expenditure, Wales 103%, Northern Ireland 112% and England 85%. The Barnett formula is unlikely to be changed in the short term because, of course, most Scottish and Welsh constituencies are represented by Labour MPs and without them Labour would not command a majority at Westminster. The English labour MPs will therefore be whipped to vote against any changes (thus perpetuating the �West Lothian question�).