Focus with a Tair 3? Manual or Bahtinov mask

[Ratlet]

I had a trial run of my Tair 3/T3i/Gem28 setup last night.  So far it's an incremental process familiarizing myself with the kit and NINA and I wasn't really aiming to gather any data last night, but I managed to get 12 minutes of data on M31 (12 x 60 second exposures).  I'm not entirely convinced by the focus though.  I know that some older glass is best focused manually and trying to minimize the halo from chromatic aberration rather than using a bahtinov mask.  Is the Tair 3 one of these?  I manually focused last night on Vega and attempted to minimize the size of the star during focusing.  Looking at the data, it appears I was slightly out, with some slight redness around the stars.

I've attached the stacked data I managed to get.  I used a constant bias of 2048 and there are no flats or darks applied (working on it).  The image was not dithered, but I was using guiding.  I did plan on trying dithering but unfortunately the wifi crapped out and Jupiter and Saturn popped their heads out so just rigged down.  There is some flaring on the stars.  I'm not sure if it is a tracking issue as it appears constant in each individual frame.  I'm unsure if this is due to not being in focus, or if it is due to me using the lens wide open at F4.5.  I've attached a very roughly processed image from my 12 minutes of data (It is my first 'proper' astrophoto.

So, any tips for focusing with a Tair 3?

Is the flaring on the stars due to tracking or is it focus or the lens wide open?