Help understanding Latin sentence structure

tl;dr - (the lack of) formal Latin sentence structure confuses me, are there any rules at all? If not, what can I do to better understand the order/meaning of what I'm reading?

I've just started reading the Lingua Latina, and although I'm doing well at figuring out what everything means, the lack of formal sentence structure confuses and frustrates me and is the number one thing hindering my comprehension of the language. I'm a very rule and internal-logic oriented person so the lack of consistency in Latin sentences makes it hard for me to learn.

I've teased out some rules, like a noun and a name right next to each other means "the [noun] of [name]" and that, like in Spanish, adjectives follow the noun they modify, such as in "fluvius parvus (small river)." However, I've noticed that the latter isn't always consistent itself, and nothing else seems to even obey the semblance of rules.

For example, the sentence "Sparta in Graecia est." is like many of the simple sentences in the book, and follows the pattern of "[noun] [preposition] [object] [verb]." However, apparently the sentence "Sparta est in Graecia." is just as valid. Sometimes I think I start to see a pattern, like "oh, the noun is in the front, the verb is in the back, and you work your way backwards from the verb" and then other times I think "I guess I can read this left to right like English?" and then other times one sentence will have me jumping between the front and then the middle AND reading left to right.

Some more examples, "In familia Iulii sunt multi servi Graeci multaque ancillae Graecae." I know that it means "In the family of Iulius, there are multiple Greek servants and multiple Greek maids." The first four words read left to right, with the verb right in the middle, but the phrase "multi servi Graeci" seems to jump from multi to Graeci to servi, which makes me question what I thought I knew about how Latin adjectives work. Isn't multi an adjective modifying servi? Shouldn't it follow servi rather than precede?

And as for the phrase "Cuius servus est Davus?" I know that it means "Who's servant is Davus?" but I cannot for the life of me figure out how to derive that meaning from that sentence with what I know about Latin grammar.

Any help is greatly appreciated!