Asymmetric Logic-grid "Brentwood Puzzle": What are these people doing?

Not yet an answer, but just clearing up what is found in the puzzle.

We know that Loti is a surname, but we are not given explicit information on the rest.

We can use social norms to guess that the first names of the men are;

• Gianni
• Carlos
• Anthony

while the women are;

• Sachi
• Donna
• Mary

This leaves the following as last names:

• Lau
• Pimentelli
• Knutson
• Rendler
• Toriseza
• Loti

Is this too presumptuous?

There are 12 tasks. These are;

• Send an overnight package
• Buy stamps
• Complain about the mail carrier
• Fill out a change of address form
• Buy a money order
• Send a airmail to Tibet
• Send books 4th class
• Pick up a package
• Send an insured package
• Add postage to the meter
• Pick up a registered letter
• Send an item parcel post

The clues then are;

1. The first person is a woman.
2. Carlos wants to send an overnight package.
3. Lau is just ahead of Pimentelli.
4. Lau and Pimentelli are the same sex.
5. Gianni is two places ahead of the person who wants to buy stamps.
6. Knutson is the opposite sex of Rendler.
7. Knutson isn't the person who wanted to complain about a mail carrier.
8. The six people, not necessarily in the same order are - Anthony, Donna, the person who wants to fill out a change-of-address form, the one who wants to buy a money order, the one who wants to send Airmail to Tibet and the second person in the line.
9. The four tasks of the last two people in line, not necessarily in the same order are - sending books fourth class, buying a money order, picking up a package and complaining about a mail carrier.
10. The person who wants to send books fourth class is just behind a person of the same sex.
11. Mary is just behind a person who wants to send an insured package.
12. The person who wants to send Airmail to Tibet is either two places ahead of or two places behind the one who wants to add postage to his or her meter.
13. Anthony isn't two places behind the who wants to pickup a registered letter.
14. Toriseza is two places ahead of the person who wants to pick up a package.
15. Knutson isn't just ahead of the person who wants to send an item parcel post.

It is possible to solve this puzzle, using only 2 guesses (in each case between 2 possibilities) using a more or less standard logic grid.

Whether it is possible to solve without guessing, i.e. by using a more clever logic-grid, I don't know.

In any case, here is the solution I found:

Step 1:

Assuming the first names can be directly correlated to the sex of individuals (as posited by @Trenin) and using the clues mentioned in the image above, we get the above result. Notice that on the left side I have introduced an auxilliary grid which keeps tabs on whether a row is Male or Female. Moving on...

Step 2:

Using the clues mentioned above (clue numbers according to @Trenin) we get the above result. The yellow colorings indicate that a single person cannot have both colorings.

Step 3:

I have now introduced another auxilliary box which keeps track of the possible orderings of Males and Females in the line. Yellow rows are not possible. To the right of this box are the clues used for this deduction. At this point I got stuck and had to guess.

Step 4:

This quickly led to a contradiction.

Step 5:

I now got stuck again.

Step 6:

This led to the contradiction shown above.

Step 7:

I'd be very interested to know if assymetric logic grids like this, i.e. where N objects have more than 1 choice each and/or less than N choices each, are possible to set up in a logic grid, similar to normal logic-grids.