What do ほどしかない and 行かないといけないから mean?

Question

I have problems with two grammar constructions that I don't know.
The first is ほどしかない and the following is the sentence:

手の爪ほどしかない小ささで、僕が確かめた限り、1〜4階層のモンスターから出てくるのはみんなこんなものだ

It is not larger nail of one hand and as far as I have verified the same, are all this as those that come out from 1 to 4 classes of monsters.

“ほどしかない小ささ” does it mean “as small as”?

The second grammar construction is 行かないといけないから and the following is the sentence:

最初に仕留めた二匹のところにも行かないといけないから、呆けている時間はないんだった

I first had to go where there were two killed and I was completely absorbed by it, because there was no time

Does this grammar construction “行かないといけないから” mean “must go?”

Answer 1

手の爪ほどしかない小ささで、僕が確かめた限り、1〜4階層のモンスターから出てくるのはみんなこんなものだ。
It's just about the size of a fingernail, and as far as I have checked, the ones (items?) that come from the monsters in Layers 1–4 are all like this.

• ～ほど: about ～
• ～しかない: only, as small as

A more literal translation of 手の爪ほどしかない would be "only about the size of a fingernail", but "as small as a fingernail" is perhaps fine, too.

最初に仕留めた二匹のところにも行かないといけないから、呆けている時間はないんだった。
I have to go to the place of the two (monsters(?)) I hunted first, so there is no time to idle.

You seem to be having trouble with the basic usage of ～から. AだからB means "B because A" or "A, therefore/so B."

行かないといけない means, yes, "have to go," and it's a very common pattern. See this question.

And this た at the end of the sentence does not represent past tense, but indicates he has just realized the fact ("there is no time"). (See ④ in this article)