So, one thing I'm having troubling understanding (and would like some help with) is how the skills function. I get that there are a couple of tiers: basic, trained, +10, and +20. What I'd like some help on is understanding when skills can be used with or without penalty. From my noobish understanding, this is how I'm reading it....

If the PC doesn't have the basic of the skill, he cannot use it.

If the PC has it as at the basic level, he can use it at a -20 to the characteristic.

If the PC has it at the trained level, he can use it at no penalty to the characteristic.

+10 and +20 are self evident.

Basic skill may be attempted by anyone. If they have training in the basic skill it may be attempted at the base stat level, if they don't have training it would be tested at 1/2 the base stat. These skills can be trained up to +10 or +20 as normal. If a skill is not "basic" it may not be attempted without training.

Dodge is an example of a basic skill. Anyone can attempt to get out of the way of being hit.

For example you have a 40 agility, with no training you dodge on a 20, with training you dodge on a 40.

Literacy is not a basic skill, so some training is required to be able to read.

So...examples help me out a lot (bear with me, sorry)

Basic

If the Astartes wants to use inquiry to try and pick up some rumors from the PDF at some outpost, he could do so because it is a basic skill but at a negative 1/2 to the charaterstic value because he isn't trained. If the Astartes spends xp on the general advance table on inquiry, he becomes trained and avoid the penalty in the future, right?

Advanced

Now our Astartes wants to use tech-use to hotwire a door. But he doesn't have tech-use as a trained skill so he cannot make the attempt. The Astartes could train tech-us depending on his specialty and/or general advances.

So...examples help me out a lot (bear with me, sorry)

Basic

If the Astartes wants to use inquiry to try and pick up some rumors from the PDF at some outpost, he could do so because it is a basic skill but at a negative 1/2 to the charaterstic value because he isn't trained. If the Astartes spends xp on the general advance table on inquiry, he becomes trained and avoid the penalty in the future, right?

Advanced

Now our Astartes wants to use tech-use to hotwire a door. But he doesn't have tech-use as a trained skill so he cannot make the attempt. The Astartes could train tech-us depending on his specialty and/or general advances.

Yes and yes