If there had been a 269/269 tie

[True Federalist (진정한 연방 주의자)]

And an abstention is as good a vote against whoever is leading.  It takes 26 States to win the Presidency in the house and 51 Senators to win the Vice Presidency in the Senate, no matter how many of them abstain.

[True Federalist (진정한 연방 주의자)]

The Senate would have voted for VP, correct? My assumption is that this would have lead to a Romney/Biden administration. Then possibly Biden taking on Romney in 2016, VP versus pres?

A man can dream.

That assumes a 269-269 tie with the Congressional elections unchanged.  In all likelihood if there had been a tie in the Electoral College, the Republicans would have also done better in the Congress.  That wouldn't affect the House result, but it could affect the Senate.  It takes 51 Senators to elect a Vice President, so the most interesting result would be a 50-50 tie or 50-49 with King (I-ME) abstaining,  The Senate would have continued under the Democratic leadership from the first seventeen days in which the Vice President could have broken the tie on who gets to be PPT and then Leahy would have remained PPT with there being no Vice President.  Altho the applecart would have been spilt when Lautenberg died and Christie appoints Chiesa and the Senate then votes in Hatch as PPT and Ryan as VP both being sworn in shortly after Chiesa.

[True Federalist (진정한 연방 주의자)]

New Jersey and Nevada were also split. Both candidates would each get a vote. To my calculation would be 300 EV for Romney if the House were to vote on the presidency with two electoral votes being awarded for each state won.

In a house vote electoral votes do not matter. The election is decided by house delegation. So if Cynthia Lummis votes for Romney that's one vote, as it it one delegation. If the California representatives all vote for Obama that's is still one vote as it is also one delegation. Therefore is Minnesota, Nevada and New Jersey have split delegations their delegation could not vote, hence the problem stated by this thread.

So it comes down to who wins more states in the House?

Almost, it comes down to who wins a majority of states in the House.  If no one can win a majority, they have to vote again.  However, the GOP controls outright a majority of delegations in the 113th Congress. Assuming no House election results changed and all Representatives voted with their party, Romney would have won the House vote 29-18-3 with a margin 3 greater than the 26 needed to win.

[True Federalist (진정한 연방 주의자)]

The Virginia Plan was for the House to elect the president. Do you know if it meant whichever candidate won more states within the House or if it came down to the popular vote within the House?

Neither.  The Founding Fathers were blithering idiots when it came to politics and political parties.  The idea of national political parties over such a large nation as ours struck them as both absurd and dangerous.  There were those who fully expected that once Washington left office most elections would be decided in the House with the Electoral College serving as a means to select five nominees to be discussed by the House.  The idea that people would campaign for the office of president was something most them failed to consider.

However, as far as electing a National Executive was concerned, the Virginia plan called for the National Legislature to elect him without specifying the exact method, tho likely it would have been the two houses sitting jointly and electing him.  In many ways the Electoral College is nothing more than a second congress elected every fourth year for the sole purpose of choosing a President without making him a creature of Congress.