Question 1

Can they be used when on the telephone or with head phones or do they need to be removed before putting anything up against your ear?

Accepted Answer

Hearing aids whistle when the microphone is blocked, or the emitted sound feeds back into the microphone.  You can make them whistle by putting your finger over the microphone to prove the point.
This microphone is the big black hole at the top in the image.  It faces straight up, making it usable in either ear.
If you do not press so hard that the phone covers the top, or presses your ear to your head, or that hair covers the top (microphone) it will not whistle.
Another reason they whistle is when clogged; the equivalent of blocking the microphone.  Note there are cleaning tools with brush and fine needle to pick flakes out.
Wax gets pressed into the domes and clog too,  No whistle, but decreased to no sound, and extra garbled sounding.
Clean your aid each day as a minimum or each battery change.
Behind The Ear (BTE) aids traditionally were designed to blast high volume for severe hearing loss, thus the large battery sizes and capacities.
To increase volume, the closer the dome is to the ear drum the louder.  Nowadays advertised as 'Senior' aids.  Domes come in different sizes so you can get one that is comfortable, and one that inserts farther than the largest one does if it helps.
Haven't heard of it, but if a soft dome should come off inside, simply get a trusted friend to remove it with tweezers.

Question 2

Is there replacement rubber ends for the bte hearing aid?

Accepted Answer

Search Amazon>>>
Hearing Aid Domes

Question 3

what is the battery size?

Accepted Answer

Diameter 11.6mm Height 5.6mm
L = Alkaline, = 110mAh-150mAh.  
S= Silver Oxide = 170mAh-200mAh.
Any of the following will work and meet the above parameters:
AG13/SG13
LR44/LR154
6135-99-792-8475 (NSN)(alkaline)
6135-99-651-3240 (NSN)(S)
A76/S76/EPX76
157/303[157]/357
1128MP, 208–904, A-76, A613, AG14,
AG-14, CA18, CA19, CR44, D76A,
G13A, G13-A, GDA76, GP76A, GPA7,
GPA75, GPA76, GPS76A, KA, KA76, AG76,
L1154, L1154C, L1154F, L1154G,
L1154H, LR44G, LR44GD, LR44H,
MS76H, PX76A, PX675A, RPX675,
RW82, SB-F9, V13G, 357A

Question 4

I have ringing in my ear Will it work for ringing in ears

Accepted Answer

Tinnitus is a problem with the bones in the ear that manifests as sound (described mostly as ringing), so this is not designed to counteract that.  
There are more sophisticated hearing aids that may help you.
Most hearing aid stores give free tests.  For many years there have been machines that do the testing that the technician can adjust during the test to show you whether they can design a hearing aid for your tinnitus or not.  In other words, the result should be known and it is not taking a chance paying for a device that doesn't work for you.

ASIN	B00II6ZHLA
Battery Description	Non-rechargeable batteries
Best Sellers Rank	284,032 in Health & Personal Care ( See Top 100 in Health & Personal Care ) 461 in Hearing Amplifiers
Brand Name	MEDca
Colour	Beige
Compatible Devices	Smartphone, Tablet, Television
Control Type	Button Control
Customer Reviews	3.4 3.4 out of 5 stars (316)
Fit Type	Behind-the-Ear
Headphone Folding Features	Behind-The-Ear
Manufacturer	MEDca
Material	Plastic
Model Name	BD26595
Model Number	BD26595
Noise Control	None
Part Number	tin2
Power Source	Battery Powered
Product Style	Behind The Ear
Rechargeable Batteries Included?	No
Strap Type	Behind-the-Ear Hook
Unit Count	1 count

MEDca Hearing Personal Sound Enhancer

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