Question about third tone sandhi in two specific cases
To the first question, I think 3rd tones are only full when its in the end of the sentences.

To the second question, I think it depends on how you do the segmentations. The last character in every parts will be 3rd tone while other are 2nd tones.

Let's say 米老鼠 would be segged as 米 / 老鼠, so the tones would be [3, 2, 3].

Some other examples: 剪指甲 would be segged as 剪 / 指甲, so the tones would be [3, 2, 3].

"我有好幾本火影忍者的漫畫" is a sentence, and the first nine characters are 3rd tones. It can be segged as 我有 / 好幾本 / 火影 / 忍者 , and the tone is

[2,3 / 2,2,3 / 2,3 / 2,3 ].

"展覽館小老鼠很口渴只好找井水洗水果 " is another sentence, and all the characters are 3rd tones. It can be segged as 展覽館 / 小 / 老鼠 / 很 / 口渴 / 只好 / 找 / 井水 / 洗 / 水果, and the tones is

[2,2,3 / 3 / 2,3 / 3 / 2,3 / 2,3 / 3 / 2,3 / 3 / 2,3]