questions for some words

Question

tengo una lista de cosas para hacer. - can i say 'que hacer' instead of para hacer?

un paseo muy bonito al lado del mar. - can i say 'junto al mar' instead of al lado del mar?
Después, voy a ver el Capitolio, un edificio blanco y grande. - do we always add 'y' between 2 adjectives and more even when the english translation does not?

Answer

Hi Ashlyn, I think you are thinking of “Tengo que hacer una lista de cosas,” which would translate as “I have to do a list of things.” This construction is used [Tener + Que + Infinitive] is used to express an obligation. The sentence in the lesson is saying something different i.e. “I have a list of things [for] to do.” Por always goes in front of the verb in these expressions.

I am fairly sure that al lado del mar would be fine. It is just the difference of beside the sea and next to the sea. Note however “al lado del mar” is using the masculine for sea which is normal, though al mar is also acceptable in certain instances; so you might say “junto del mar.”

As for the question about adjectives I’m not entirely sure if it is always the case, but in this case definitely. I hope this helps. Saludos. John

Answer

Hola Ashlyn and John
Thanks John for your clarification - there are a couple of things though that I'd like to comment: 
you can also "cosas que hacer" as well as "cosas para hacer" - with the verb "tener" this is very common. We form infinitive clauses of this type, they are here in this lesson. Have a look.
"Al lado del mar" and "junto al mar" are both correct, maybe with "junto al mar" we perceive it as closer to the sea, but this is probably just my perception. I'd say they are completely interchangeable. 
As per dropping the "y" with two adjectives, you can do that in Spanish with two adjectives but it is not common to drop the conjunction "y":
Tengo un perro grande y negro.
I have a big black dog. 
Saludos
Inma