I sprayed some of my car 2 winters ago. That was cellulose but i
assume this will be the same for tekaloid:
The cold weather means the paint takes longer to go off - which gave
it a much better finish in my case.

I used generic etch primer from the paint shop. I have sprayed it, but
Lee did his with a roller.
It is indeed 2 part. I did mine in the summer and it went off at the
same speed as the normal primer i used on top of it.

The etch primer is also only supposed to last for a few days once
mixed, so dont mix it all at once if you are taking your time over the
whole landy.

You should be OK unless you paint in sub zero temperatures, cold can be
a problem, damp and frost is the real killer.
(I won't bleat on about you should only paint in warmer conditions).

Cold weather will extend the drying time and stiffen your paint, though
you could add a little Tekaloid fast thinner (TN02) to help ease paint
application.

Heating the can is an old remedy but unfortunately only shortlived,
this method is more suitable when varnishing because heat will dissolve
some of the stearates, though stearates (sediment) is usualy only found
in cheap varnish not paint.

What you should do prior to painting is keep the paint indoors for a few
days to bring the paint to a natural working room temperature as this
will make all the difference and it would be advisable to use two tins
of paint, when one starts to thicken with the cold, then you start using
the other tin, then put the paint you've just used back indoors to heat
up while your using the other warmer thinner paint.

Force heating paint will make it workable for the first couple of panels
but it will quickly become stiff (creating an uneven paint film) and
almost unusable, whereas paint at a favourable room temperature stays
workable for a longer period.

Etch primer is pretty foolproof and doesn't really need any special
attention other than avoiding damp panels obviously.

You can use almost any primer including the Tekaloid range of primers
viewed here: http://www.stephen.hull.btinternet.co.uk/data.html but it
may not be necessary to use a conventional primer, it may be easier to
apply a mixed 50% gloss 50% undercoat after applying acid etch, primers
usually require rubbing down to remove deep brush-marks, whereas gloss
and  undercoat mixed 50-50 leaves no brush-marks and often only requires
a dry flat before applying gloss over the top.

Stephen.