Hi. You may want to check if you have any particular options in FSUIPC, it could influence the qnh. Please bear in mind that ivao weather servers are often offline, that might be the cause of your problem too.
As for the TCAS... check that you have selected show all in the pmdg simulation options in the CDU.
Once you turn the xpdr to the last detent and press TFC on the efis, you should see ta only in blue on the ND while on the ground and TFC while airborne.
If it's there, the tcas works. Still, the tcas shows traffic closer than 20 nm, while ivao's tcas goes as far as 40 nm.