1. I am not a caique owner, BUT, the following is true of most birds and I do have some experience with caiques---even though I have never owned one myself:
If they don't get along and you want to keep the status-quo, then you are looking at 4-6 hours with your current bird, PLUS another 4 with your new bird separately (most people don't have that kind of time on their hands for the next 30 years)---To maintain what you have going on now, you are looking at 8-12 hours out-of-cage supervision for both birds when their individual out-of-cage times are combined. They (especially the caique in question) often appear to become jealous and they can be territorial (all birds can/do jealousy/territorial things, but caiques seem to be a bit more prone towards interactions with with other birds that come off as confrontational, even if that isn't the intention of said interaction-style)...It is also likely that your current bird will take it personally if you get a new bird and all of the sudden he gets locked up for longer periods of time in favor of a new bird...It is possible that they COULD get along, but you have to plan as if they won't in order to determine whether you have the time to commit to keeping both. Honestly, I wouldn't bank on them being friends (because many birds just don't get along and because a baby caique is also going to change its behavior at maturation). Parrots notice when you spend less time with them--especially when it can be attributed to the presence of a new person or bird that is "stealing" your attention from them-- when bonded tightly to a human, this behavior is often magnified.
Now, could you get by with under 4-6 hours out-of-cage-time per bird? Probably (but you are still looking at 3 hours minimum per bird in the worst-case-scenario). Your current bird is already accustomed to the 4-6 and if he associates a decrease in his happiness with a new bird's arrival, he also may get jealous of the new bird and develop an attitude with you and/or the new "house-mate". Once the caique bonds with you, he may resent your current bird for the same reasons.
Another thing to consider is the age of your current bird. A lot changes at puberty, and so if you are dealing with a younger bird, you may find yourself busier than you thought when current bird becomes sexually mature.
Then there is the fact that so much will change between now and 30 years from now...There is really know way for you to commit to 2 long-lived birds who may not get along until you have a place of your own and a steady job (you can't predict your hours). How can you know 5 years ahead of time what your adult work schedule will be, or if perhaps you will meet someone who wants children (another time consuming affair)? As you get older, so will your parents, so they will not always be able to help with the birds depending on their age/health in your future.
Of course people can have birds and children, but all of these changes etc can be really hard to envision when still at school/living with family support. A lot changes over time, so whatever you do, consider that the time they need is non-negotiable, but neither is your getting a job one day and moving into your own place eventually.
In the next 5-15 years, you will likely have 1) a job that requires at least 7 hours a day (in order to pay for your housing and birds +anything else) 2) a husband/wife/partner who requires time of his/her own with you, 3) BILLS, bills, bills, 4) Possible children of your own with nap-times and play-dates/after-school activities...and 5) you likely will have to move between now and then (and moving with birds is a complicated affair). Travel opportunities are also limited/altered significantly.
I know that sounds negative, but it's something to think about...Not to mention the steep increase in veterinary care/housing/food/toy expenses you will face (and the fact that people in their 20s are often dealing with student loan debt, rental payments, or even diaper/formula bills for a human baby).
You already have 1 bird for which you are responsible, but 2 would be significantly more work/time/money etc.
I am not trying to focus on the negative, but it is important to fully consider all possible outcomes before making a 30 year commitment to 2 birds.
