The Four Letter Sequence

This is a 3 Part Question GoodLuck

A puzzle in a local newspaper gave a series of numerals in the following four, four-letter sequences:

A B C D
D E H G
F B A K
H C F J

The rules for answering the Question:

Each row Represents a sequence and some of them could be the same.
Any letter that occurs in more than one sequence represents the same numeral in each of those sequences.
The numerals 6,7,8 and 9 are each represented once in each of the four sequences, no other numerals are represented.
The first letter of any sequence can represent only 6 or 7.
The last letter of any Sequence cannot be 6

With those rules in mind...

Question 1:
What numeral is represented by A?

Question 2:
Which of the following i s a possible order of the numerals for the last sequence?

6 7 8 9
8 6 7 9
7 9 6 8
7 8 6 9
6 8 7 9

Question 3:
If the additional rule is given that K represents 9, which of the following must be true?

G represents 8
E represents 8
B represents 8
J represents 9
F represents 9

Like I said goodluck, these are tough.

I'll take a look at it tomorrow

6

6879

b=8

A must be 6

The last row can be 6879, but the next rule eliminates that as well.

Therefore, B=8