I love Mr. Resetti and this game gives me precious few chances to see him so I took the liberty of gathering some data about the Fountain, golden/silver axes and Serena:
-You cannot access the fountain until the day after it's installed as Tortimer is locked in front of it.
-You throw an axe in by standing in front of it and swinging the axe.
-Wifi visitors cannot throw axes into the fountain, though I have yet to test this myself.
-You can only throw in one axe per day.
-Serena is a bitchy little cocktease. If she's a "goddess", she harkens back to the days of Greek goddesses who loved to play with mortals for their own amusement.
-Serena will always ask you what kind of axe you threw in. Answer honestly or she'll just blow you off and likely won't give you your axe back.
-Even if you DO answer honestly, she still may not give you your axe back.
-The whole "encounter" is completely 100% random: you can answer honestly and the only thing that will happen is Serena will hand you back your axe, or she may keep it because she loves being a bitch.
-On occasion, she will ask you if she's being "enough like a goddess" and will give you a sliding bar to choose "Sure am" or "No!". No matter what you choose, the outcome is 100% random. You can answer the question the same way twice and Serena will react differently each time, once taking your answer to heart and the next time doing nothing but getting mad at you.
-Bottom line, you could potentially spend every last day you play AC:CF trying to get the golden axe but to no avail. She'll give you a silver axe every now and then, but be prepared to toss endless axes into this fountain and have Serena toy with you every single day.
-It IS possible to get the golden axe on the VERY first day of having the fountain in your town, as I did after 30+ resets, but the odds are extremely unlikely. I don't know if accepting a silver axe from her will reduce your chances of getting a golden axe later, but if she offered one, I'd take it.
-When I finally got the golden axe from her, I had reset after getting 3 chances to take a silver axe in about 30 attempts and I was willing to settle for the silver axe instead.
-The golden axe isn't worth doing what I did, as I was losing my mind by the end and trying hard to not fall asleep. The silver axe doesn't break either, and the only advantage the golden axe is that it swings slightly faster, meaning you can hit money rocks faster. However, I tested it and got 8,100 bells from a money rock, the exact same amount I get with my silver shovel.
-I don't even consider the golden axe a status symbol at this point as "earning" it is based entirely upon luck. The golden watering can is the REAL status symbol as it requires you to have a perfect town for 16 days and requires actual effort.
Long story short, I want my 700,000 bells back. Axes are 400 bells and can be used to cut down 10-15 trees or so. You could buy 1,750 axes with that much money, and cut down (at the lowest) 17,500 trees before justifying the cost of paying for the fountain.
The windmill/lighthouse do absolutely nothing, from everything I've heard, so after you've added the bridge, don't feel any pressure to donate unless you're going for one of the feathers.
Also, the statue in the city is of Serena, but her eyes, when open, are empty, hollow orbs, making her look undead. I'm a bit miffed that I let this creepy, bitchy thing into my town. It doesn't help that the fountain she lives in isn't very pretty and the water running makes a strange noise that sounds very little like running water.
I preferred WW's method of having you swap rare items with visitors in your town on a quest to get the golden axe. This is more convenient but we already have a "roll of the dice" mechanic in finding Resetti's open to get the silver shovel.
The biggest irony in all of this is that the golden axe is the tool which will likely be used the least out of all tools and yet it's the most expensive to acquire. You'll cut down trees to set your town up exactly ONCE and then never need the damn thing again, except in rare occasions where a regular axe would work just fine. If there were some way to make loads of money with it, I could understand, but as it stands, it's not worth the money or the hassle.