they all have several different means.

经过 means 1、somewhere you pass by/go by, e.g. 我经过一座教堂。or 从葡萄牙坐飞机到上海要经过香港。

2、 the process of doing something, e.g. 说说你去上海旅行的经过。 here in some situations Chinese people also use 经历(经历 is a noun here, means experience. )。说说你去上海旅游的经历 have the same mean.

However, 经历过 means something you had been through/ had seen/had done e.g：他经历过两次世界大战。

in 经历过, 经历 is a verb here because it is followed with 过, and it shouldn't be the end of one sentence, it should be followed with something, like here 两次世界大战。

经历 can be used as a noun. As a noun, it can be used at the end of one sentence. like 旅游的经历

只，只有 are much easier to be distinguished.

只: is a measure word, like 一只手（one hand）

but 只 can be combined with other words and have different meanings.

只有，means only, alone, like 我只有一个儿子。

只有 usually follow with 才能 or 才有

只有...才能... means only...can... e.g. 只有人类才能写字。

只有...才有... means only...have... e.g. 只有人类才有文字。

Hope my answer could help you.

Question on Chinese Grammar