Do I have a case to get my $300 refunded for my landlord's misdiagnoses of dog hair in the coil when it was actually a bad coil?

Attorney Jonathan has given very good advice, I would just like to add that you should keep following up with LL until he releases the invoice.

what are the possibilities of both getting approved together H4 and H4-EAD with less gap in employment?

Did your employer hire an attorney to process the I-140?

Will change of employer be a problem while I am holding an approved H1B and my extension is in process?

Once the transfer is approved the old employer will/should withdraw the extension.

No, not on the visa but if the L2 receives an EAD it will be on the EAD.

Change the status from B1/B2 into E2 Treaty visa.

A person is eligible to change status in the U.S. if they meet all requirements.

Will I get interdiction ?

Please refer to the original posting for more information.

It seems like you timely submitted your visa extension request so why would you have incurred unlawful presence?

My tenant changed the keys and wont give me keys. What can I do ?

Did the tenant do so after asking you to do it?

What steps should I take next?

In nearly all cases you cannot purposefully pay rent late - this is rarely in your best interest.

Is this harassment from my landlord?

What horrible emails are you receiving from the landlord?