the slightest bit (adjective)

We use this phrase to emphasize that a quality is very small.

I’m starting to get just the slightest bit hungry.

If I felt even the slightest bit unsure, I wouldn’t be doing it.

It’s somewhat playful language that we use once in a while. A similar, and perhaps more common phrase is “the tiniest bit.”

(feeling) as to (something)

Here, “as to” is used just like “about.” 

I’m not sure as to the plan after Friday.

He’s a little worried as to what will happen after the holidays.

There’s no specific reason to use “as to” instead of “about.” We probably do it just for more variety, making our sentences more interesting. It also sounds a little more formal.

all these (weeks/months/years)

You can use “all these (weeks/months/years)” to talk about something that has been happening for a long time-- or feels like it’s been happening for a long time. The phrase also implies that the listener knows something about these weeks, months, etc, or experienced them together with the speaker. There is a shared, “insider” feeling that “many years,” for example, doesn’t have. 

I’ve been waiting all these weeks to hear back from them.

All these years I thought she didn’t like me.

You can also say “all this time” if you don’t want to specify the number of weeks, months, etc.

All this time, I’ve been saying it completely wrong.

curious (about something)

Feeling "curious about" something means wanting to know more about it.

When he was a little boy, he was always so curious about nature and animals.

You can use "curious" in this form as well:

I'm really curious what he does in his free time.

You can use the word "curiosity" to talk about this quality in someone:

What I like best about her is her curiosity.