Need help for soviet teir 1

I've got some questions that I need to be answered:

Should I merge with the conscript on penals and other squads?
How do I play the m3a1 scout car, I consistently lose it?
Which doctrines go well with t1?
Which vehicle should I get from t3 or should I go straight for the t34?

Thanks in Advance guys!

1. Conscript Merge is very powerful and you should use it with all squads (including team weapons) except Shocks. This is due to the fact that generally conscript reinforce cost is lower (cons are 20MP, combat engineers are 21MP, penals are 25MP, guards are 27MP).
Don't merge with Shocks because shocks have 1.5 armor, which they rely on to tank bullets in order to close the distance.

2. The M3A1 scout car is very strong against OKW early-game. Stick a Penal squad inside (then a Combat Engineer with a Flamer) and use it to close-range bully lone squads or burn MGs in houses (stay at long range vs Sturmpioneers). After about 6-7 min (about when OKW gets their truck down) pop the squad out and start using it as long-range fire support to help you win infantry engagements. It's okay to lose it at this point if you've already done plenty of manpower and map control damage.

3. Most doctrines are fine with T1 as it is very flexible. If you build 1-2 Conscripts, Tank Hunters is very viable. Engage hard on the enemy until you get your 3CPs, then stick PTRS on your Conscripts. Concripts become very effective against light and even medium armor, while it keeps Penals effective against infantry. Late game you get the IL-2 PTAB AT Bombing run, which is effective against tanks if it hits; try aiming for tank with engine damage or ones that are stunned.
If you don't build Conscripts, Guard Motor is extremely strong, as you can use 2CP Guards to fill in the light AT role (their anti-infantry isn't bad either), 120mm Mortars to bomb/smoke MGs, and late-game you get T-34/85s combined with Mark Target.

4. Currently it is advised to get a T-70 from T3. It is an extremely strong anti-infantry vehicle that can defeat the 222 one-on-one and also the OKW Luchs if you manage to get a jump on it. Use aggressively, but stay out of faust range, and watch for mines.
Later on in the game when medium tanks have been out for a while don't use it as aggressively; instead use its Recon Mode to give you information about where the enemy is.
Going for the T-34 isn't a bad call either, as the T-34/76 is also quite effective against infantry and isn't afraid of Axis light vehicles.