Hi.
I breastfed my last child for 6 years and never had a breastpump. You absolutely don't need one, but get one if you want.
It is perfectly possible to hand express a few ounces and give it in a cup (or bottle). This is what I did after she was 6 months.
I didnt use a steriliser either, I boiled a (small, round) tupperware in a pan, and a doidy cup, and after 10 minutes the pan was switched off and they went in the fridge.
I expressed into the tupperware and put it in the fridge with the lid on for her dad or whoever to put in the doidy cup later.
You can boil bottles and the pump up too.
This time I am planning on getting a pump so I can express milk to donate, so I'll be looking at either a Medela electric pump or considering hiring a 'hospital grade' one from the manufacturer. I need to look into cost then decide.
Breastmilk will keep in the fridge for about 5 days but it needs to be at the coldest part of the fridge (not in the door or at the front) and if you open the fridge a lot you'd be best putting the milk in a cool bag sealed up in the fridge to keep the temperature constant.
Constant fluctuation of temperature will make it go off quicker.
You can also freeze your milk for up to 6 months.
Yes it is safe to sterilise the bottles and store the milk in the bottle in the fridge, as fresh pumped breastmilk is a living substance and has antibacterial properties, so there is not the same risk of bacteria growing as there is with storing formula in bottles.
That said, whilst the baby is little, if you plan to keep milk in the fridge for more than a day I would get some breastmilk storage pots and sterilise them, put the pumped milk into them, and transfer into a freshly sterilised bottle just before you feed the baby to avoid bacteria having chance to grow on the bottle teat.
If you do plan to have others give the baby a bottle of expressed milk, it's still best to wait a minimum of 6 weeks to do that so as to not interfere with establishing breastfeeding.
Personally, I introduced bottles with my first at 10 weeks old and it still made breastfeeding more difficult and caused the baby to not want to feed at the breast (and I pretty much dried up by 4 months and they were fully bottle fed then), which is why with my second I didn't do bottles at all, I just waited until around 5/6 months and went straight to a doidy cup for expressed milk feeds.
Not meaning to scare you, but do be aware that bottles (and dummies) can make it harder to successfully breastfeed, so leave it as long as you can before introducing them and if it's purely for dad/grandma etc to bond there are loads of other things they can do (like bathing baby, having skin to skin cuddles, wearing the baby in a sling, baby massage etc).