Help! I need somebody...

...to explain Gaelic 'infinitives' to me.

- Is it the verbal noun that is used in all cases?

- Is it preceded by 'a', and does this 'a' lenite?

- Do direct object nouns and pronouns come before or after the infinitive?

I know that indirect object nouns and pronouns follow the preposition but I'm mightily confused by direct objects.
I've examined this topic in several sources including the excellent Taic but I still find all the various rules confusing.

Generally I've found that, while some parts of Gaelic are easy to grasp and memorise, the use of infinitives and the definite article are almost overwhelmingly complicated and daunting. So any help in this regard is much appreciated, tapadh leibh.

However, despite this obsession with grammar, I am taking steps to actually speak the language to people. I went to a conversation group last week and I plan on going semi-regularly to try out the stuff I've learned. Last week I realised that I need more vocab (cue horrific memories of learning lists of words - bain of my life for the last 10 years!)

Here's a clip of the Latin class in Dead Poets Society. If only learning vocab had been that fun, alas!